arm64: Kconfig: Update ARCH_EXYNOS select configs

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

I verified the .config is identical with and without this change.

Signed-off-by Will McVicker <[email protected]>

---
 arch/arm64/Kconfig.platforms | 1 -
 drivers/clk/samsung/Kconfig  | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

Quoted 4 lines · Will McVicker

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

The clock drivers are essential, you cannot disable them for a generic kernel supporting ARCH_EXYNOS. Such kernel won't work properly on platforms.

Quoted 6 lines · Krzysztof Kozlowski

Quoted 4 lines · Will McVicker

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

Quoted 2 lines

The clock drivers are essential, you cannot disable them for a generic kernel supporting ARCH_EXYNOS. Such kernel won't work properly on platforms.

Obviously it's not gonna work if the clock driver is not enabled at all. But does it work if you make the clock driver modular, and put it with all other essential driver modules in initramfs? Debugging would be hard, as the serial console driver also relies on clocks and PM Domains etc.

If not, this patch should be NAKed, until it works with a modular clock driver.

If yes, perhaps another line should be added (_before_ the other line)?

+ default m if ARCH_EXYNOS && MODULES
default y if ARCH_EXYNOS

However, many developers may want MODULES=y, but not want to bother with an initramfs. So perhaps we need a new symbol MINIMUM_GENERIC_KERNEL or so, protected by EXPERT, and make the driver default to m if that is enabled?

Quoted 7 lines · Geert Uytterhoeven

Quoted 6 lines · Krzysztof Kozlowski

Quoted 4 lines · Will McVicker

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

Quoted 8 lines

Quoted 2 lines

The clock drivers are essential, you cannot disable them for a generic kernel supporting ARCH_EXYNOS. Such kernel won't work properly on platforms.

Obviously it's not gonna work if the clock driver is not enabled at all. But does it work if you make the clock driver modular, and put it with all other essential driver modules in initramfs? Debugging would be hard, as the serial console driver also relies on clocks and PM Domains etc.

The kernel could boot without clock drivers (default settings from bootloader), probe clocks from initramfs and proceed with rootfs from eMMC/SD/net.

In theory.

However I have no reports that it ever worked. If there is such working upstream configuration, I don't mind here. Just please explain this in the commit msg.

Quoted 6 lines

If not, this patch should be NAKed, until it works with a modular clock driver.

If yes, perhaps another line should be added (_before_ the other line)?

Quoted 7 lines

+ default m if ARCH_EXYNOS && MODULES
default y if ARCH_EXYNOS

However, many developers may want MODULES=y, but not want to bother with an initramfs. So perhaps we need a new symbol MINIMUM_GENERIC_KERNEL or so, protected by EXPERT, and make the driver default to m if that is enabled?

Yeah, that's indeed a problem to solve. For most users (and distros) building kernel for Exynos this should be built-in by default.

Anyway, the option is non-selectable so it cannot be converted to "m" or disabled. And this is claimed in the commit msg:
"provide flexibilty for vendors to disable or modularize this driver."

The commit does not achieve it.

Best regards,
Krzysztof

Quoted 51 lines · Krzysztof Kozlowski

Quoted 7 lines · Geert Uytterhoeven

Quoted 6 lines · Krzysztof Kozlowski

Quoted 4 lines · Will McVicker

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

Quoted 8 lines

Quoted 2 lines

The clock drivers are essential, you cannot disable them for a generic kernel supporting ARCH_EXYNOS. Such kernel won't work properly on platforms.

Obviously it's not gonna work if the clock driver is not enabled at all. But does it work if you make the clock driver modular, and put it with all other essential driver modules in initramfs? Debugging would be hard, as the serial console driver also relies on clocks and PM Domains etc.

The kernel could boot without clock drivers (default settings from bootloader), probe clocks from initramfs and proceed with rootfs from eMMC/SD/net.

In theory.

However I have no reports that it ever worked. If there is such working upstream configuration, I don't mind here. Just please explain this in the commit msg.

Quoted 6 lines

If not, this patch should be NAKed, until it works with a modular clock driver.

If yes, perhaps another line should be added (_before_ the other line)?

Quoted 7 lines

+ default m if ARCH_EXYNOS && MODULES
default y if ARCH_EXYNOS

However, many developers may want MODULES=y, but not want to bother with an initramfs. So perhaps we need a new symbol MINIMUM_GENERIC_KERNEL or so, protected by EXPERT, and make the driver default to m if that is enabled?

Yeah, that's indeed a problem to solve. For most users (and distros) building kernel for Exynos this should be built-in by default.

Anyway, the option is non-selectable so it cannot be converted to "m" or disabled. And this is claimed in the commit msg:
"provide flexibilty for vendors to disable or modularize this driver."

The commit does not achieve it.

Quoted 2 lines

Best regards,
Krzysztof

Thanks for the reviews! As Lee has explained in his replies, the intent of this series is to provide config flexibility to create a defconfig that allows us to move out SoC specific drivers in order to create a generic kernel that can be used across multiple devices with different SoCs.

I'm sorry I added confusion by mentioning
modularization. All of these drivers that I am modifying in this series can be modularized which is an ongoing effort, but is not addressed here and I don't believe that modularizing them should be a requirement before supporting enabling/disabling them.

I will update the series with my patch that refactors the Samsung SoC drivers menuconfig to make these visible as well.

Quoted 53 lines · Will McVicker

Quoted 51 lines · Krzysztof Kozlowski

Quoted 7 lines · Geert Uytterhoeven

Quoted 6 lines · Krzysztof Kozlowski

Quoted 4 lines · Will McVicker

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

Quoted 8 lines

Quoted 2 lines

The clock drivers are essential, you cannot disable them for a generic kernel supporting ARCH_EXYNOS. Such kernel won't work properly on platforms.

Obviously it's not gonna work if the clock driver is not enabled at all. But does it work if you make the clock driver modular, and put it with all other essential driver modules in initramfs? Debugging would be hard, as the serial console driver also relies on clocks and PM Domains etc.

The kernel could boot without clock drivers (default settings from bootloader), probe clocks from initramfs and proceed with rootfs from eMMC/SD/net.

In theory.

However I have no reports that it ever worked. If there is such working upstream configuration, I don't mind here. Just please explain this in the commit msg.

Quoted 6 lines

If not, this patch should be NAKed, until it works with a modular clock driver.

If yes, perhaps another line should be added (_before_ the other line)?

Quoted 7 lines

+ default m if ARCH_EXYNOS && MODULES
default y if ARCH_EXYNOS

However, many developers may want MODULES=y, but not want to bother with an initramfs. So perhaps we need a new symbol MINIMUM_GENERIC_KERNEL or so, protected by EXPERT, and make the driver default to m if that is enabled?

Yeah, that's indeed a problem to solve. For most users (and distros) building kernel for Exynos this should be built-in by default.

Anyway, the option is non-selectable so it cannot be converted to "m" or disabled. And this is claimed in the commit msg:
"provide flexibilty for vendors to disable or modularize this driver."

The commit does not achieve it.

Quoted 8 lines

Quoted 2 lines

Best regards,
Krzysztof

Thanks for the reviews! As Lee has explained in his replies, the intent of this series is to provide config flexibility to create a defconfig that allows us to move out SoC specific drivers in order to create a generic kernel that can be used across multiple devices with different SoCs.

That's quite generic statement... or let me put it that way - we already have this ability to create a generic kernel supporting different SoCs. Exynos and other ARMv7 and ARMv8 platforms are multiplatform.

Task is done.

Please be more specific about use case and describe what exactly in current upstream multiplatform kernel is missing, what is not multiplatform enough.

Quoted 5 lines

I'm sorry I added confusion by mentioning
modularization. All of these drivers that I am modifying in this series can be modularized which is an ongoing effort, but is not addressed here and I don't believe that modularizing them should be a requirement before supporting enabling/disabling them.

Since the disabling the driver for a kernel supporting Exynos does not make any sense, then making it at least modular unfortunately it is a requirement.

Quoted 2 lines

I will update the series with my patch that refactors the Samsung SoC drivers menuconfig to make these visible as well.

I would first recommend to really describe your use case because my questions about this are still unanswered.

Quoted 67 lines · Krzysztof Kozlowski

Quoted 53 lines · Will McVicker

Quoted 51 lines · Krzysztof Kozlowski

Quoted 7 lines · Geert Uytterhoeven

Quoted 6 lines · Krzysztof Kozlowski

Quoted 4 lines · Will McVicker

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

Quoted 8 lines

Quoted 2 lines

The clock drivers are essential, you cannot disable them for a generic kernel supporting ARCH_EXYNOS. Such kernel won't work properly on platforms.

Obviously it's not gonna work if the clock driver is not enabled at all. But does it work if you make the clock driver modular, and put it with all other essential driver modules in initramfs? Debugging would be hard, as the serial console driver also relies on clocks and PM Domains etc.

The kernel could boot without clock drivers (default settings from bootloader), probe clocks from initramfs and proceed with rootfs from eMMC/SD/net.

In theory.

However I have no reports that it ever worked. If there is such working upstream configuration, I don't mind here. Just please explain this in the commit msg.

Quoted 6 lines

If not, this patch should be NAKed, until it works with a modular clock driver.

If yes, perhaps another line should be added (_before_ the other line)?

Quoted 7 lines

+ default m if ARCH_EXYNOS && MODULES
default y if ARCH_EXYNOS

However, many developers may want MODULES=y, but not want to bother with an initramfs. So perhaps we need a new symbol MINIMUM_GENERIC_KERNEL or so, protected by EXPERT, and make the driver default to m if that is enabled?

Yeah, that's indeed a problem to solve. For most users (and distros) building kernel for Exynos this should be built-in by default.

Anyway, the option is non-selectable so it cannot be converted to "m" or disabled. And this is claimed in the commit msg:
"provide flexibilty for vendors to disable or modularize this driver."

The commit does not achieve it.

Quoted 8 lines

Quoted 2 lines

Best regards,
Krzysztof

Thanks for the reviews! As Lee has explained in his replies, the intent of this series is to provide config flexibility to create a defconfig that allows us to move out SoC specific drivers in order to create a generic kernel that can be used across multiple devices with different SoCs.

That's quite generic statement... or let me put it that way - we already have this ability to create a generic kernel supporting different SoCs. Exynos and other ARMv7 and ARMv8 platforms are multiplatform.

Quoted 1 line

Task is done.

multi_v7_defconfig and ARMv8's defconfig are bloated monoliths which provide limited flexibility. Good for testing and messing around - not much good for real products.

Quoted 4 lines

Please be more specific about use case and describe what exactly in current upstream multiplatform kernel is missing, what is not multiplatform enough.

The use-case is GKI. A realistic middle-ground between fully open source and real-world usage of the Linux kernel in a competitive technical arena. GKI aims to be as close to Mainline as possible, whilst allowing hardware vendors to supply their own software containing their perceived competitive edge and/or supporting not-yet-released hardware platforms.

If you end up over-constraining the ability to configure the kernel in useful/meaningful ways, that makes one of the main (best intention) aims of GKI, (i.e. to have an upstream first ethos in order to be as close to upstream as possible) much more difficult.

I put in a lot of effort to ensure GKI doesn't end up as just another fork of the Linux kernel. So far, so good, but flexibility and understanding is key.

Quoted 9 lines

Quoted 5 lines

I'm sorry I added confusion by mentioning
modularization. All of these drivers that I am modifying in this series can be modularized which is an ongoing effort, but is not addressed here and I don't believe that modularizing them should be a requirement before supporting enabling/disabling them.

Since the disabling the driver for a kernel supporting Exynos does not make any sense, then making it at least modular unfortunately it is a requirement.

I can go with that.

Quoted 3 lines

Quoted 2 lines

I will update the series with my patch that refactors the Samsung SoC drivers menuconfig to make these visible as well.

Quoted 2 lines

I would first recommend to really describe your use case because my questions about this are still unanswered.

Hopefully my replies have helped somewhat.

Happy to discuss further if required.

If all else fails, feel free to ping me on IRC (lag).

Quoted 69 lines · Lee Jones

Quoted 67 lines · Krzysztof Kozlowski

Quoted 53 lines · Will McVicker

Quoted 51 lines · Krzysztof Kozlowski

Quoted 7 lines · Geert Uytterhoeven

Quoted 6 lines · Krzysztof Kozlowski

Quoted 4 lines · Will McVicker

COMMON_CLK_SAMSUNG is selected by ARCH_EXYNOS which forces this config to be built-in when ARCH_EXYNOS is enabled. Switch the logic to use a "default y if ARCH_EXYNOS" to provide flexibilty for vendors to disable or modularize this driver.

Quoted 8 lines

Quoted 2 lines

The clock drivers are essential, you cannot disable them for a generic kernel supporting ARCH_EXYNOS. Such kernel won't work properly on platforms.

Obviously it's not gonna work if the clock driver is not enabled at all. But does it work if you make the clock driver modular, and put it with all other essential driver modules in initramfs? Debugging would be hard, as the serial console driver also relies on clocks and PM Domains etc.

The kernel could boot without clock drivers (default settings from bootloader), probe clocks from initramfs and proceed with rootfs from eMMC/SD/net.

In theory.

However I have no reports that it ever worked. If there is such working upstream configuration, I don't mind here. Just please explain this in the commit msg.

Quoted 6 lines

If not, this patch should be NAKed, until it works with a modular clock driver.

If yes, perhaps another line should be added (_before_ the other line)?

Quoted 7 lines

+ default m if ARCH_EXYNOS && MODULES
default y if ARCH_EXYNOS

However, many developers may want MODULES=y, but not want to bother with an initramfs. So perhaps we need a new symbol MINIMUM_GENERIC_KERNEL or so, protected by EXPERT, and make the driver default to m if that is enabled?

Yeah, that's indeed a problem to solve. For most users (and distros) building kernel for Exynos this should be built-in by default.

Anyway, the option is non-selectable so it cannot be converted to "m" or disabled. And this is claimed in the commit msg:
"provide flexibilty for vendors to disable or modularize this driver."

The commit does not achieve it.

Quoted 8 lines

Quoted 2 lines

Best regards,
Krzysztof

Thanks for the reviews! As Lee has explained in his replies, the intent of this series is to provide config flexibility to create a defconfig that allows us to move out SoC specific drivers in order to create a generic kernel that can be used across multiple devices with different SoCs.

That's quite generic statement... or let me put it that way - we already have this ability to create a generic kernel supporting different SoCs. Exynos and other ARMv7 and ARMv8 platforms are multiplatform.

Quoted 5 lines

Quoted 1 line

Task is done.

multi_v7_defconfig and ARMv8's defconfig are bloated monoliths which provide limited flexibility. Good for testing and messing around - not much good for real products.

I am not saying about defconfigs. I am saying that ARMv8 platform is multiplatform so we already solved the problem Will mentioned. :)

Quoted 11 lines

Quoted 4 lines

Please be more specific about use case and describe what exactly in current upstream multiplatform kernel is missing, what is not multiplatform enough.

The use-case is GKI. A realistic middle-ground between fully open source and real-world usage of the Linux kernel in a competitive technical arena. GKI aims to be as close to Mainline as possible, whilst allowing hardware vendors to supply their own software containing their perceived competitive edge and/or supporting not-yet-released hardware platforms.

<grumpy mode>
Therefore the use case is to not contribute anything upstream around ARCH_EXYNOS but use it in millions of devices downstream with hundreds of out-of-tree modules. The use case is to make life easy for the vendor and out-of-tree code, not for the upstream. Instead of promoting upstreaming, or leaning towards usptream in some balanced way, the use case is to entirely go to out-of-tree.

I am not thinking here about edge or not-yet-released platforms but "ancient" in terms of current SoC business, e.g. 3-5 years old. </grumpy mode>

Quoted 5 lines

If you end up over-constraining the ability to configure the kernel in useful/meaningful ways, that makes one of the main (best intention) aims of GKI, (i.e. to have an upstream first ethos in order to be as close to upstream as possible) much more difficult.

GKI encourages core kernel changes to be upstreamed but it is effectively the nail in the coffin of upstreaming vendor SoC changes. There is simply no incentive for less-cooperative vendor to upstream it's modules (except usual benefits like code quality and user support which are not important for less-cooperative vendors).

The kernel should be configured mainly towards mainline platforms. Not the other way around. This of course does not stop it for supporting out-of-tree code, but I guess you also know that what's out-of-tree, it does not exist. :)

Quoted 19 lines

I put in a lot of effort to ensure GKI doesn't end up as just another fork of the Linux kernel. So far, so good, but flexibility and understanding is key.

Quoted 9 lines

Quoted 5 lines

I'm sorry I added confusion by mentioning
modularization. All of these drivers that I am modifying in this series can be modularized which is an ongoing effort, but is not addressed here and I don't believe that modularizing them should be a requirement before supporting enabling/disabling them.

Since the disabling the driver for a kernel supporting Exynos does not make any sense, then making it at least modular unfortunately it is a requirement.

I can go with that.

Quoted 3 lines

Quoted 2 lines

I will update the series with my patch that refactors the Samsung SoC drivers menuconfig to make these visible as well.

Quoted 8 lines

Quoted 2 lines

I would first recommend to really describe your use case because my questions about this are still unanswered.

Hopefully my replies have helped somewhat.

Happy to discuss further if required.

If all else fails, feel free to ping me on IRC (lag).

Thanks Lee, you described the use case. In general I like it and support it, except for what I wrote in the other mail.

Vendor does not contribute much therefore there is no balance in upstreaming. Since none of other vendor's platforms are supported, I am looking only at what is supported. From that perspective - the change proposed by Will and previous guys, does not have much sense.

My perspective probably would change a lot if vendor did contribute some of its non-edge platforms (3-5 years old)... especially that unlike few community guys (e.g. PostmarketOS), vendor has shit-tons of money and the hardware manuals. :)

Instead of pushing this change, please let's give some incentive to the vendor for upstreaming anything.

Quoted 8 lines

Thanks Lee, you described the use case. In general I like it and support it, except for what I wrote in the other mail.

Vendor does not contribute much therefore there is no balance in upstreaming. Since none of other vendor's platforms are supported, I am looking only at what is supported. From that perspective - the change proposed by Will and previous guys, does not have much sense.

Quoted 4 lines

My perspective probably would change a lot if vendor did contribute some of its non-edge platforms (3-5 years old)... especially that unlike few community guys (e.g. PostmarketOS), vendor has shit-tons of money and the hardware manuals. :)

But no incentive to upstream code old (dead) platforms that they no longer make money from. We're not talking about kind-hearted individuals here. These are business entities.

What is the business incentive to put hundreds of thousands of dollars into something with no RoI?

Quoted 3 lines

Instead of pushing this change, please let's give some incentive to the vendor for upstreaming anything.

Again, you're being specific. We would also like/need to make the same kinds of changes to other vendor configurations. One's which do contribute significantly at their own cost.

The technical reasoning cannot be different because you do or don't like the way the company operates. Try to detach a little from your feelings during discussions which should be purely technical.

Quoted 1 line

Vendors are not able to upstream all functionality right away

Quoted 17 lines · Lee Jones

Quoted 8 lines

Thanks Lee, you described the use case. In general I like it and support it, except for what I wrote in the other mail.

Vendor does not contribute much therefore there is no balance in upstreaming. Since none of other vendor's platforms are supported, I am looking only at what is supported. From that perspective - the change proposed by Will and previous guys, does not have much sense.

Quoted 4 lines

My perspective probably would change a lot if vendor did contribute some of its non-edge platforms (3-5 years old)... especially that unlike few community guys (e.g. PostmarketOS), vendor has shit-tons of money and the hardware manuals. :)

But no incentive to upstream code old (dead) platforms that they no longer make money from. We're not talking about kind-hearted individuals here. These are business entities.

Quoted 2 lines

What is the business incentive to put hundreds of thousands of dollars into something with no RoI?

Before you mentioned business entities refrain from upstreaming recent hardware. You question upstreaming not that recent, so basically business entity will claim it has zero incentives working with upstream.

Actually there are incentives for both cases - better code quality for the pieces being base for future devices, selling mainline supported hardware to other businesses, eventually less work for themselves around keeping code in sync with mainline. All these are of course difficult to measure from business perspective.

Quoted 7 lines

Quoted 3 lines

Instead of pushing this change, please let's give some incentive to the vendor for upstreaming anything.

Again, you're being specific. We would also like/need to make the same kinds of changes to other vendor configurations. One's which do contribute significantly at their own cost.

Yes, I am specific because we talk here about specfic Kconfig changes for one specific ARM sub-architecture. Same set of changes can be applied to other SoCs and usually have more sense there because number of upstream platforms is bigger.

If you have 10 different pinctrl drivers, you might decide to narrow the defconfigs to subset of it. If you have 2-3, the extra complexity does not matter and you just enable all of them. That's also decision we made few years ago internally in Samsung.

Quoted 3 lines

The technical reasoning cannot be different because you do or don't like the way the company operates. Try to detach a little from your feelings during discussions which should be purely technical.

Quoted 1 line · I mentioned the less-contributing vendor arguments because you said:

Quoted 1 line

Vendors are not able to upstream all functionality right away

That's the side-topic in this discussion.

Technically, all supported Exynos platforms require selecting ARCH_EXYNOS and require all drivers selected by ARCH_EXYNOS. If you mention some unsupported out-of-tree platforms, which I cannot audit/see/use, it is not a valid reason to change statement above. Make them supported, available to audit and check and statement above stops being valid.

Best regards,
Krzysztof

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

There are no .config differences with this change. The configs SOC_SAMSUNG, EXYNOS_CHIPID, EXYNOS_PM_DOMAINS, and EXYNOS_PMU still remain enabled by default.

Signed-off-by Will McVicker <[email protected]>

---
 arch/arm64/Kconfig.platforms | 4 ----
 drivers/soc/samsung/Kconfig  | 4 ++++
 2 files changed, 4 insertions(+), 4 deletions(-)

arch/arm64/Kconfig.platforms +0 -4

index 3a66ed43088d..6a006490c9b9 100644
@@ -91,14 +91,10 @@ config ARCH_BRCMSTB
 
 config ARCH_EXYNOS
        bool "ARMv8 based Samsung Exynos SoC family"
-       select EXYNOS_CHIPID
-       select EXYNOS_PM_DOMAINS if PM_GENERIC_DOMAINS
-       select EXYNOS_PMU
        select HAVE_S3C_RTC if RTC_CLASS
        select PINCTRL
        select PINCTRL_EXYNOS
        select PM_GENERIC_DOMAINS if PM
-       select SOC_SAMSUNG
        help
          This enables support for ARMv8 based Samsung Exynos SoC family.
 

drivers/soc/samsung/Kconfig +4 -1

index 5745d7e5908e..9402c02bc9de 100644
@@ -4,6 +4,7 @@
 #
 menuconfig SOC_SAMSUNG
        bool "Samsung SoC driver support" if COMPILE_TEST
+       default y if ARCH_EXYNOS
 
 if SOC_SAMSUNG
 

@@ -15,6 +16,7 @@ config EXYNOS_ASV_ARM
 config EXYNOS_CHIPID
        bool "Exynos ChipID controller and ASV driver" if COMPILE_TEST
        depends on ARCH_EXYNOS || COMPILE_TEST
+       default y if ARCH_EXYNOS
        select EXYNOS_ASV_ARM if ARM && ARCH_EXYNOS
        select MFD_SYSCON
        select SOC_BUS

@@ -24,6 +26,7 @@ config EXYNOS_CHIPID
 config EXYNOS_PMU
        bool "Exynos PMU controller driver" if COMPILE_TEST
        depends on ARCH_EXYNOS || ((ARM || ARM64) && COMPILE_TEST)
+       default y if ARCH_EXYNOS
        select EXYNOS_PMU_ARM_DRIVERS if ARM && ARCH_EXYNOS
 
 # There is no need to enable these drivers for ARMv8

@@ -34,6 +37,7 @@ config EXYNOS_PMU_ARM_DRIVERS
 config EXYNOS_PM_DOMAINS
        bool "Exynos PM domains" if COMPILE_TEST
        depends on (ARCH_EXYNOS && PM_GENERIC_DOMAINS) || COMPILE_TEST
+       default y if (ARCH_EXYNOS && PM_GENERIC_DOMAINS)
 
 config SAMSUNG_PM_DEBUG
        bool "Samsung PM Suspend debug"
--

2.33.0.464.g1972c5931b-goog

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

There are no .config differences with this change. The configs SOC_SAMSUNG, EXYNOS_CHIPID, EXYNOS_PM_DOMAINS, and EXYNOS_PMU still remain enabled by default.

Signed-off-by Will McVicker <[email protected]>

---
 arch/arm64/Kconfig.platforms | 4 ----
 drivers/soc/samsung/Kconfig  | 4 ++++
 2 files changed, 4 insertions(+), 4 deletions(-)

arch/arm64/Kconfig.platforms +0 -0

index 3a66ed43088d..6a006490c9b9 100644

Quoted 5 lines · Will McVicker

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

This is not true. Vendors cannot disable these options as they are not visible.

Although I understand that Arnd prefers this way and I do not object it, but your explanation is incorrect.

Quoted 7 lines · Krzysztof Kozlowski

Quoted 5 lines · Will McVicker

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

Quoted 2 lines

This is not true. Vendors cannot disable these options as they are not visible.

Good point, well made.

Quoted 2 lines

Although I understand that Arnd prefers this way and I do not object it, but your explanation is incorrect.

--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services

Linaro.org │ Open source software for Arm SoCs
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Quoted 10 lines · Lee Jones

Quoted 7 lines · Krzysztof Kozlowski

Quoted 5 lines · Will McVicker

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

Quoted 7 lines

Quoted 2 lines

This is not true. Vendors cannot disable these options as they are not visible.

Good point, well made.

Quoted 2 lines

Although I understand that Arnd prefers this way and I do not object it, but your explanation is incorrect.

Thanks Krzysztof for the reviews! I'm sorry I missed the whole "hidden configs" part. I'll upload the series to include the fix that refactos the Samsung SoC drivers menuconfig which will address that and allow one to enable/disable those configs. I'm going to hold off though until we hash out the rest of the discussion in the cover letter email.

Quoted 19 lines · Will McVicker

Quoted 10 lines · Lee Jones

Quoted 7 lines · Krzysztof Kozlowski

Quoted 5 lines · Will McVicker

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

Quoted 7 lines

Quoted 2 lines

This is not true. Vendors cannot disable these options as they are not visible.

Good point, well made.

Quoted 2 lines

Although I understand that Arnd prefers this way and I do not object it, but your explanation is incorrect.

Quoted 6 lines

Thanks Krzysztof for the reviews! I'm sorry I missed the whole "hidden configs" part. I'll upload the series to include the fix that refactos the Samsung SoC drivers menuconfig which will address that and allow one to enable/disable those configs. I'm going to hold off though until we hash out the rest of the discussion in the cover letter email.

No, please first read our discussions, including Lee's and Geert's comments. The drivers should not be converted to modules or made visible if such configuration does not work. If it works, please describe your testing setup.

All these drivers are *necessary* for a multiplatform kernel supporting Exynos platforms, therefore disabling them does not make any sense (if you support Exynos platform). If your kernel does not support Exynos platform, just do not select ARCH_EXYNOS and problem disappears because none of these drivers will be visible and selected.

Unless you describe here some out-of-tree kernel which wants ARCH_EXYNOS, because vendor did not upstream it's code, but you do not want existing Exynos upstream drivers. We do not support such configuration. Please push your lovely vendor to work with upstream. That's the only solution.

It's the third time this abuse re-usage of ARCH_EXYNOS appears and the same as before - the vendor does not like to upstream stuff. There are few guys trying to upstream recent Samsung SoC support by themself (ping me for contacts if you would like to participate) but the one party which should be doing it - the lovely vendor - does not actually participate and instead sends ridiculous patches like this one here... or like this [1] [2].

Nope, please work with upstreaming SoC support, instead of abusing ARCH_EXYNOS for out of tree code from the vendor.

[1]
https://lore.kernel.org/linux-samsung-soc/[email protected]/

[2]
https://lore.kernel.org/linux-usb/[email protected]/

Best regards,
Krzysztof

Quoted 27 lines · Krzysztof Kozlowski

Quoted 25 lines · Will McVicker

Quoted 10 lines · Lee Jones

Quoted 7 lines · Krzysztof Kozlowski

Quoted 5 lines · Will McVicker

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

Quoted 7 lines

Quoted 2 lines

This is not true. Vendors cannot disable these options as they are not visible.

Good point, well made.

Quoted 2 lines

Although I understand that Arnd prefers this way and I do not object it, but your explanation is incorrect.

Thanks Krzysztof for the reviews! I'm sorry I missed the whole "hidden configs" part. I'll upload the series to include the fix that refactos the Samsung SoC drivers menuconfig which will address that and allow one to enable/disable those configs. I'm going to hold off though until we hash out the rest of the discussion in the cover letter email.

Quoted 4 lines

No, please first read our discussions, including Lee's and Geert's comments. The drivers should not be converted to modules or made visible if such configuration does not work. If it works, please describe your testing setup.

Modules *should* work. William is going to try it out.

Might need to lean-on for some testing on different H/W though.

Quoted 21 lines

All these drivers are *necessary* for a multiplatform kernel supporting Exynos platforms, therefore disabling them does not make any sense (if you support Exynos platform). If your kernel does not support Exynos platform, just do not select ARCH_EXYNOS and problem disappears because none of these drivers will be visible and selected.

Unless you describe here some out-of-tree kernel which wants ARCH_EXYNOS, because vendor did not upstream it's code, but you do not want existing Exynos upstream drivers. We do not support such configuration. Please push your lovely vendor to work with upstream. That's the only solution.

It's the third time this abuse re-usage of ARCH_EXYNOS appears and the same as before - the vendor does not like to upstream stuff. There are few guys trying to upstream recent Samsung SoC support by themself (ping me for contacts if you would like to participate) but the one party which should be doing it - the lovely vendor - does not actually participate and instead sends ridiculous patches like this one here... or like this [1] [2].

Quoted 2 lines

Nope, please work with upstreaming SoC support, instead of abusing ARCH_EXYNOS for out of tree code from the vendor.

One of the on-going issues that GKI aims to solve pertains to the disparity between what upstream engineers would like to be upstreamed (i.e. everything) and what vendors can upstream (i.e. most things).

The old Open Source vs Business (i.e. products/real-life) struggle!

Vendors are not able to upstream all functionality right away, as it would give away their perceived edge on the competition (i.e. other vendors). This is something we just have to accept as it will *never* change.

GKI attempts to solve this issue by providing a generic core containing all of the elements required to get every supported platform bootstrapped to a point where modules can be loaded and additional functionality can be brought in. GKI provides all of the modules available from the upstream kernel BUT allows them to be overwritten/swapped-out by modules containing code (new/shiny unreleased value-add) that the vendors do not wish to share (yet).

Clever, eh!

As I've explained before, the trigger for all of this was SERIAL_SAMSUNG which is required for early console on supported Samsung platforms i.e. this symbol *has* to be built-in.

In order for
this to built-in ARCH_EXYNOS has to be enabled due to the listed dependencies in Kconfig. And since ARCH_EXYNOS 'selects' all of these different extra symbols, it means they too will be built-in, meaning that a) the core binary will be unnecessarily bloated and b) vendors who wish to overwrite/replace this functionality with their non-shareable value-add, are not able to do so.

Going forward, it sounds like the best approach that will make everyone happy, providing it's technically feasible, is to enable these added (sometimes required, other times superfluous) symbols as loadable modules.

Quoted 34 lines · Lee Jones

Quoted 31 lines · Krzysztof Kozlowski

Quoted 19 lines · Will McVicker

Quoted 10 lines · Lee Jones

Quoted 7 lines · Krzysztof Kozlowski

Quoted 5 lines · Will McVicker

Switch the default logic to enable SOC_SAMSUNG and it's sub-configs to be enabled by default via "default y if ARCH_EXYNOS" versus being selected by the ARCH_EXYNOS config directly. This allows vendors to disable these configs if they wish and provides additional flexibility to modularize them in the presence of a generic kernel.

Quoted 7 lines

Quoted 2 lines

This is not true. Vendors cannot disable these options as they are not visible.

Good point, well made.

Quoted 2 lines

Although I understand that Arnd prefers this way and I do not object it, but your explanation is incorrect.

Quoted 6 lines

Thanks Krzysztof for the reviews! I'm sorry I missed the whole "hidden configs" part. I'll upload the series to include the fix that refactos the Samsung SoC drivers menuconfig which will address that and allow one to enable/disable those configs. I'm going to hold off though until we hash out the rest of the discussion in the cover letter email.

No, please first read our discussions, including Lee's and Geert's comments. The drivers should not be converted to modules or made visible if such configuration does not work. If it works, please describe your testing setup.

Quoted 3 lines

Modules *should* work. William is going to try it out.

Might need to lean-on for some testing on different H/W though.

I can help, few other folks from Samsung can help as well.

Quoted 27 lines

Quoted 20 lines

All these drivers are *necessary* for a multiplatform kernel supporting Exynos platforms, therefore disabling them does not make any sense (if you support Exynos platform). If your kernel does not support Exynos platform, just do not select ARCH_EXYNOS and problem disappears because none of these drivers will be visible and selected.

Unless you describe here some out-of-tree kernel which wants ARCH_EXYNOS, because vendor did not upstream it's code, but you do not want existing Exynos upstream drivers. We do not support such configuration. Please push your lovely vendor to work with upstream. That's the only solution.

It's the third time this abuse re-usage of ARCH_EXYNOS appears and the same as before - the vendor does not like to upstream stuff. There are few guys trying to upstream recent Samsung SoC support by themself (ping me for contacts if you would like to participate) but the one party which should be doing it - the lovely vendor - does not actually participate and instead sends ridiculous patches like this one here... or like this [1] [2].

Quoted 2 lines

Nope, please work with upstreaming SoC support, instead of abusing ARCH_EXYNOS for out of tree code from the vendor.

One of the on-going issues that GKI aims to solve pertains to the disparity between what upstream engineers would like to be upstreamed (i.e. everything) and what vendors can upstream (i.e. most things).

Quoted 6 lines

The old Open Source vs Business (i.e. products/real-life) struggle!

Vendors are not able to upstream all functionality right away, as it would give away their perceived edge on the competition (i.e. other vendors). This is something we just have to accept as it will *never* change.

Sure, I understand. Balance, compromise, not perfectness.

However now it is heavily in-balanced since vendor did upstream only one change - UFS drivers for new SoC - since 2017. One change. Nothing else, nothing for older SoC, nothing for newer.

All other work is done by the community, not by the vendor.

Not sure how to qualify Sam's Exynos850 work, but even if counting it, there will be just two changes from vendor.

This is not acceptable, this is not a balanced approach.

Quoted 8 lines

GKI attempts to solve this issue by providing a generic core containing all of the elements required to get every supported platform bootstrapped to a point where modules can be loaded and additional functionality can be brought in. GKI provides all of the modules available from the upstream kernel BUT allows them to be overwritten/swapped-out by modules containing code (new/shiny unreleased value-add) that the vendors do not wish to share (yet).

Quoted 5 lines

Clever, eh!

As I've explained before, the trigger for all of this was SERIAL_SAMSUNG which is required for early console on supported Samsung platforms i.e. this symbol *has* to be built-in.

Actually SERIAL_SAMSUNG does not have to be built-in. It is necessary for built-in only for debugging or development, not for real products.

Unlike other drivers which have to be built-in, e.g. clocks or pinctrl, or heavily tested whether setup from initrd works. Plus not breaking distros who like to have everything as module (solution from Geert?)...

Quoted 7 lines

In order for
this to built-in ARCH_EXYNOS has to be enabled due to the listed dependencies in Kconfig. And since ARCH_EXYNOS 'selects' all of these different extra symbols, it means they too will be built-in, meaning that a) the core binary will be unnecessarily bloated and b) vendors who wish to overwrite/replace this functionality with their non-shareable value-add, are not able to do so.

I am sorry, but this is not reflecting status we want to have in usptream. Everything selected by ARCH_EXYNOS *has to be selected* for supported platforms. Since vendor does not contribute anything new (except mentioned one work for UFS), we are not going to sacrifice supported mainline platforms for a non-cooperative out-of-tree unknown platforms.

Quoted 4 lines

Going forward, it sounds like the best approach that will make everyone happy, providing it's technically feasible, is to enable these added (sometimes required, other times superfluous) symbols as loadable modules.

Not entirely. What actually would make everyone happy and it is still technically feasible is for a multi-billion company with thousands of engineers to contribute something. Let's start with a little bit. From billions of dollars and thousands of engineers we won't expect too much, right?

Quoted 7 lines · Krzysztof Kozlowski

Quoted 3 lines · Lee Jones

As I've explained before, the trigger for all of this was SERIAL_SAMSUNG which is required for early console on supported Samsung platforms i.e. this symbol *has* to be built-in.

Actually SERIAL_SAMSUNG does not have to be built-in. It is necessary for built-in only for debugging or development, not for real products.

Right. And in the early stages, GKI is used for early (non-released) H/W (this is also the part of the reason these differences can't be upstreamed early/now/yet) and sometimes changes break things requiring low-level debugging techniques to solve (inc. early console).

Quoted 3 lines

Unlike other drivers which have to be built-in, e.g. clocks or pinctrl, or heavily tested whether setup from initrd works. Plus not breaking distros who like to have everything as module (solution from Geert?)...

We don't know which drivers *need* to be built-in yet.

Clocks is probably not a good example even, since the power-on default is most likely all-on, which is fine. Pinctrl remains to be seen.

Quoted 8 lines

Quoted 7 lines

In order for
this to built-in ARCH_EXYNOS has to be enabled due to the listed dependencies in Kconfig. And since ARCH_EXYNOS 'selects' all of these different extra symbols, it means they too will be built-in, meaning that a) the core binary will be unnecessarily bloated and b) vendors who wish to overwrite/replace this functionality with their non-shareable value-add, are not able to do so.

Quoted 6 lines

I am sorry, but this is not reflecting status we want to have in usptream. Everything selected by ARCH_EXYNOS *has to be selected* for supported platforms. Since vendor does not contribute anything new (except mentioned one work for UFS), we are not going to sacrifice supported mainline platforms for a non-cooperative out-of-tree unknown platforms.

The is the part of the discussion that is the most contentious.

Ideally we wouldn't have to enable any ARCH_* explicitly. Greg has mentioned this publicly on a number of discussions. However, removing the dependencies (from Kconfig in this case) is in contention with other user's use-cases. No one wants to be asked seemingly irrelevant configuration questions during the config stages of a kernel build.

So we are forced to enable ARCH_* to have our requirements built-in (ARCH_EXYNOS for SAMSUNG_SERIAL [early console] in this case). Unfortunately, this comes with additional cruft that we *might* not want (resulting in bloat) or that we wish to overwrite with more featureful driver modules. We can't do that if these features are built-in.

Quoted 14 lines · Lee Jones

Quoted 7 lines · Krzysztof Kozlowski

Quoted 3 lines · Lee Jones

As I've explained before, the trigger for all of this was SERIAL_SAMSUNG which is required for early console on supported Samsung platforms i.e. this symbol *has* to be built-in.

Actually SERIAL_SAMSUNG does not have to be built-in. It is necessary for built-in only for debugging or development, not for real products.

Right. And in the early stages, GKI is used for early (non-released) H/W (this is also the part of the reason these differences can't be upstreamed early/now/yet) and sometimes changes break things requiring low-level debugging techniques to solve (inc. early console).

Quoted 8 lines

Quoted 3 lines

Unlike other drivers which have to be built-in, e.g. clocks or pinctrl, or heavily tested whether setup from initrd works. Plus not breaking distros who like to have everything as module (solution from Geert?)...

We don't know which drivers *need* to be built-in yet.

Clocks is probably not a good example even, since the power-on default is most likely all-on, which is fine. Pinctrl remains to be seen.

Clocks is an excellent example: if a clock is missing, the driver will fail to probe (unless the clock is considered optional by the driver), regardless of the power-on or boot loader defaults. With fw_devlinks=on (which is the default now, and developed by a Google engineer (GKI or another division?)), the driver won't even get to the probing point.

Pinctrl is different, as unless I'm mistaken, drivers will still probe if the pin control driver is missing, so they will work if the power-on or boot loader defaults of pin control are fine.

Switching the default config logic of PINCTRL_EXYNOS to use "default y if ARCH_EXYNOS" versus having ARCH_EXYNOS directly select the config. This gives vendors the flexibility to disable the config or modularize it in the presence of a generic kernel.

Verified this change doesn't effect the .config.

Signed-off-by Will McVicker <[email protected]>

---
 arch/arm64/Kconfig.platforms    | 1 -
 drivers/pinctrl/samsung/Kconfig | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

arch/arm64/Kconfig.platforms +0 -1

index 6a006490c9b9..a884e5da8b0f 100644
@@ -93,7 +93,6 @@ config ARCH_EXYNOS
 	bool "ARMv8 based Samsung Exynos SoC family"
 	select HAVE_S3C_RTC if RTC_CLASS
 	select PINCTRL
-	select PINCTRL_EXYNOS
 	select PM_GENERIC_DOMAINS if PM
 	help
 	  This enables support for ARMv8 based Samsung Exynos SoC family.

drivers/pinctrl/samsung/Kconfig +0 -0

index dfd805e76862..483acb8ac1f6 100644

Quoted 4 lines · Will McVicker

Switching the default config logic of PINCTRL_EXYNOS to use "default y if ARCH_EXYNOS" versus having ARCH_EXYNOS directly select the config. This gives vendors the flexibility to disable the config or modularize it in the presence of a generic kernel.

Reasoning is incorrect. This is an essential driver which CANNOT be disabled for any kernel having ARCH_EXYNOS or ARCH_S5PV210. You are trying to prepare it for some out-of-tree code? Please, upstream your code instead.

Quoted 25 lines

Verified this change doesn't effect the .config.

Signed-off-by Will McVicker <[email protected]>

---
 arch/arm64/Kconfig.platforms    | 1 -
 drivers/pinctrl/samsung/Kconfig | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

arch/arm64/Kconfig.platforms +0 -1

index 6a006490c9b9..a884e5da8b0f 100644
@@ -93,7 +93,6 @@ config ARCH_EXYNOS
 	bool "ARMv8 based Samsung Exynos SoC family"
 	select HAVE_S3C_RTC if RTC_CLASS
 	select PINCTRL
-	select PINCTRL_EXYNOS
 	select PM_GENERIC_DOMAINS if PM
 	help
 	  This enables support for ARMv8 based Samsung Exynos SoC family.

drivers/pinctrl/samsung/Kconfig +0 -0

index dfd805e76862..483acb8ac1f6 100644

drivers/pinctrl/samsung/Kconfig config PINCTRL_EXYNOS · line 15

Quoted 4 lines

drivers/pinctrl/samsung/Kconfig +1 -0

@@ -12,6 +12,7 @@ config PINCTRL_EXYNOS
 	bool "Pinctrl common driver part for Samsung Exynos SoCs"
 	depends on OF_GPIO
 	depends on ARCH_EXYNOS || ARCH_S5PV210 || COMPILE_TEST
+	default y if ARCH_EXYNOS

default ARCH_EXYNOS || ARCH_S5PV210
... and update all mach Kconfigs.

drivers/pinctrl/samsung/Kconfig config PINCTRL_EXYNOS · line 18

Quoted 4 lines

drivers/pinctrl/samsung/Kconfig +0 -0

 	select PINCTRL_SAMSUNG
 	select PINCTRL_EXYNOS_ARM if ARM && (ARCH_EXYNOS || ARCH_S5PV210)
 	select PINCTRL_EXYNOS_ARM64 if ARM64 && ARCH_EXYNOS

Best regards,
Krzysztof

Switching the default config logic of PINCTRL_EXYNOS to use "default y if ARCH_EXYNOS" versus having ARCH_EXYNOS directly select the config. This gives vendors the flexibility to disable the config or modularize it in the presence of a generic kernel.

Verified this change doesn't effect the .config.

Signed-off-by Will McVicker <[email protected]>

Switches the default config logic of HAVE_S3C_RTC to use "default y if (ARCH_EXYNOS && RTC_CLASS)" versus having ARCH_EXYNOS directly select it. This provides vendors flexibility to disable the config if desired or modularize it in the presence of a generic kernel.

Verified this change doesn't impact the .config.

Signed-off-by Will McVicker <[email protected]>

---
 arch/arm64/Kconfig.platforms | 1 -
 drivers/rtc/Kconfig          | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

arch/arm64/Kconfig.platforms +0 -1

index a884e5da8b0f..f9f829aab511 100644
@@ -91,7 +91,6 @@ config ARCH_BRCMSTB
 
 config ARCH_EXYNOS
 	bool "ARMv8 based Samsung Exynos SoC family"
-	select HAVE_S3C_RTC if RTC_CLASS
 	select PINCTRL
 	select PM_GENERIC_DOMAINS if PM
 	help

drivers/rtc/Kconfig +1 -0

index e1bc5214494e..40afdb37d2a5 100644
@@ -1406,6 +1406,7 @@ config RTC_DRV_OMAP
 
 config HAVE_S3C_RTC
 	bool
+	default y if (ARCH_EXYNOS && RTC_CLASS)
 	help
 	  This will include RTC support for Samsung SoCs. If
 	  you want to include RTC support for any machine, kindly

Signature · 1 line

2.33.0.464.g1972c5931b-goog

Switches the default config logic of HAVE_S3C_RTC to use "default y if (ARCH_EXYNOS && RTC_CLASS)" versus having ARCH_EXYNOS directly select it. This provides vendors flexibility to disable the config if desired or modularize it in the presence of a generic kernel.

Verified this change doesn't impact the .config.

Signed-off-by Will McVicker <[email protected]>

---
 arch/arm64/Kconfig.platforms | 1 -
 drivers/rtc/Kconfig          | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

arch/arm64/Kconfig.platforms +0 -0

 	select PINCTRL
 	select PM_GENERIC_DOMAINS if PM
 	help

drivers/rtc/Kconfig +0 -0

index e1bc5214494e..40afdb37d2a5 100644

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

To address this without impacting the existing behavior, this series switches the default config logic for the offending configs to use "default y if ARCH_EXYNOS" versus having ARCH_EXYNOS directly select them. I have verified that these patches do not impact the default aarch64 .config.

Will McVicker (4):
clk: samsung: change COMMON_CLK_SAMSUNG default config logic
soc: samsung: change SOC_SAMSUNG default config logic
pinctrl: samsung: change PINCTRL_EXYNOS default config logic
rtc: change HAVE_S3C_RTC default config logic

 arch/arm64/Kconfig.platforms    | 7 -------
 drivers/clk/samsung/Kconfig     | 1 +
 drivers/pinctrl/samsung/Kconfig | 1 +
 drivers/rtc/Kconfig             | 1 +
 drivers/soc/samsung/Kconfig     | 4 ++++
 5 files changed, 7 insertions(+), 7 deletions(-)

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

To address this without impacting the existing behavior, this series switches the default config logic for the offending configs to use "default y if ARCH_EXYNOS" versus having ARCH_EXYNOS directly select them. I have verified that these patches do not impact the default aarch64 .config.

Will McVicker (4):
clk: samsung: change COMMON_CLK_SAMSUNG default config logic
soc: samsung: change SOC_SAMSUNG default config logic
pinctrl: samsung: change PINCTRL_EXYNOS default config logic
rtc: change HAVE_S3C_RTC default config logic

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

Quoted 5 lines

To address this without impacting the existing behavior, this series switches the default config logic for the offending configs to use "default y if ARCH_EXYNOS" versus having ARCH_EXYNOS directly select them. I have verified that these patches do not impact the default aarch64 .config.

Yep, this is what you did but it does not match the described problem. You are not solving it but doing something else.

Quoted 7 lines

Will McVicker (4):
clk: samsung: change COMMON_CLK_SAMSUNG default config logic
soc: samsung: change SOC_SAMSUNG default config logic
pinctrl: samsung: change PINCTRL_EXYNOS default config logic
rtc: change HAVE_S3C_RTC default config logic

I received only two patches from this set. Please resend following get_maintainers.pl script.

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

Quoted 4 lines

To address this without impacting the existing behavior, this series switches the default config logic for the offending configs to use "default y if ARCH_EXYNOS" versus having ARCH_EXYNOS directly select them. I have verified that these patches do not impact the default aarch64 .config.

Yep, this is what you did but it does not match the described problem. You are not solving it but doing something else.

Quoted 5 lines

Will McVicker (4):
clk: samsung: change COMMON_CLK_SAMSUNG default config logic
soc: samsung: change SOC_SAMSUNG default config logic
pinctrl: samsung: change PINCTRL_EXYNOS default config logic
rtc: change HAVE_S3C_RTC default config logic

Quoted 11 lines · Krzysztof Kozlowski

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

The wording is unfortunate. The reason for this change doesn't have much to do with kernel modules.

Let's go back in time 18 months or so when Greg KH submitted this [0] patch, which you Acked. Greg was trying to solve the problem of not having to enable ARCH_EXYNOS on kernels which are designed to be platform agnostic (sometimes called Generic Kernels). For some reason SERIAL_SAMSUNG is the only symbol with these dependencies, so the solution seemed simple and straight forward at the time.

However, For sound reasons Geert NACKed the patch.

Quoting from [1] he says:

"A generic kernel will include Samsung SoC support, hence PLAT_SAMSUNG or ARCH_EXYNOS will be enabled."

However, since the entry for ARCH_EXYNOS *insists* on building-in a bunch of other symbols (via 'select') which will be unused in most cases, this is not a currently acceptable approach for many Generic Kernels due to size constraints.

What this patch does is migrates those symbols from being 'select'ed (always built-in with no recourse) to 'default y'. Where the former cannot be over-ridden, but the latter can be via a vendor's defconfig/fragment.

I doubt many (any?) of these symbols can be converted to kernel modules anyway, as they are required very early on in the boot sequence.

Quoted 24 lines · Lee Jones

Quoted 11 lines · Krzysztof Kozlowski

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

The wording is unfortunate. The reason for this change doesn't have much to do with kernel modules.

Let's go back in time 18 months or so when Greg KH submitted this [0] patch, which you Acked. Greg was trying to solve the problem of not having to enable ARCH_EXYNOS on kernels which are designed to be platform agnostic (sometimes called Generic Kernels). For some reason SERIAL_SAMSUNG is the only symbol with these dependencies, so the solution seemed simple and straight forward at the time.

Quoted 6 lines

However, For sound reasons Geert NACKed the patch.

Quoting from [1] he says:

"A generic kernel will include Samsung SoC support, hence PLAT_SAMSUNG or ARCH_EXYNOS will be enabled."

Yes, it's correct reasoning. There is also one more use-case - non-upstreamed (out of tree) platform which wants to use Exynos-specific drivers. Something like was happening with Apple M1 except that it got upstreamed and we do not care much about out-of-tree.

Quoted 4 lines

However, since the entry for ARCH_EXYNOS *insists* on building-in a bunch of other symbols (via 'select') which will be unused in most cases, this is not a currently acceptable approach for many Generic Kernels due to size constraints.

In the mainline kernel there is no such use case. If you want to have Exynos-whatever-driver (e.g. SERIAL_SAMSUNG or S3C RTC), you should select ARCH_EXYNOS because otherwise it does not make any sense. Zero sense. Such kernel won't work.

It makes sense only if there is some other work, hidden here, where someone might want to have SERIAL_SAMSUNG or S3C RTC without ARCH_EXYNOS. Although GKI is not that work because GKI kernel will select ARCH_EXYNOS. It must select ARCH_EXYNOS if it wants to support Exynos platforms.

Therefore I expect first to bring this "some other work, hidden here" to broader audience, so we can review its use case.

Quoted 4 lines

What this patch does is migrates those symbols from being 'select'ed (always built-in with no recourse) to 'default y'. Where the former cannot be over-ridden, but the latter can be via a vendor's defconfig/fragment.

It cannot be overridden by vendor fragment because options are not visible. You cannot change them.

The patch does nothing in this regard (making them selectable/possible to disable), which is why I complained.

Quoted 3 lines

I doubt many (any?) of these symbols can be converted to kernel modules anyway, as they are required very early on in the boot sequence.

True, some could, some not. Also some platforms are set up via bootloader, so actually could "survive" till module is loaded from some initrd.

Quoted 24 lines · Lee Jones

Quoted 11 lines · Krzysztof Kozlowski

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

The wording is unfortunate. The reason for this change doesn't have much to do with kernel modules.

Let's go back in time 18 months or so when Greg KH submitted this [0] patch, which you Acked. Greg was trying to solve the problem of not having to enable ARCH_EXYNOS on kernels which are designed to be platform agnostic (sometimes called Generic Kernels). For some reason SERIAL_SAMSUNG is the only symbol with these dependencies, so the solution seemed simple and straight forward at the time.

Quoted 6 lines

However, For sound reasons Geert NACKed the patch.

Quoting from [1] he says:

"A generic kernel will include Samsung SoC support, hence PLAT_SAMSUNG or ARCH_EXYNOS will be enabled."

Yes, it's correct reasoning. There is also one more use-case - non-upstreamed (out of tree) platform which wants to use Exynos-specific drivers. Something like was happening with Apple M1 except that it got upstreamed and we do not care much about out-of-tree.

Quoted 5 lines

However, since the entry for ARCH_EXYNOS *insists* on building-in a bunch of other symbols (via 'select') which will be unused in most cases, this is not a currently acceptable approach for many Generic Kernels due to size constraints.

In the mainline kernel there is no such use case. If you want to have Exynos-whatever-driver (e.g. SERIAL_SAMSUNG or S3C RTC), you should select ARCH_EXYNOS because otherwise it does not make any sense. Zero sense. Such kernel won't work.

It makes sense only if there is some other work, hidden here, where someone might want to have SERIAL_SAMSUNG or S3C RTC without ARCH_EXYNOS. Although GKI is not that work because GKI kernel will select ARCH_EXYNOS. It must select ARCH_EXYNOS if it wants to support Exynos platforms.

Therefore I expect first to bring this "some other work, hidden here" to broader audience, so we can review its use case.

Quoted 5 lines

What this patch does is migrates those symbols from being 'select'ed (always built-in with no recourse) to 'default y'. Where the former cannot be over-ridden, but the latter can be via a vendor's defconfig/fragment.

It cannot be overridden by vendor fragment because options are not visible. You cannot change them.

The patch does nothing in this regard (making them selectable/possible to disable), which is why I complained.

Quoted 1 line

Quoted 3 lines

I doubt many (any?) of these symbols can be converted to kernel modules anyway, as they are required very early on in the boot sequence.

True, some could, some not. Also some platforms are set up via bootloader, so actually could "survive" till module is loaded from some initrd.

Quoted 71 lines · Krzysztof Kozlowski

Quoted 24 lines · Lee Jones

Quoted 11 lines · Krzysztof Kozlowski

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

The wording is unfortunate. The reason for this change doesn't have much to do with kernel modules.

Let's go back in time 18 months or so when Greg KH submitted this [0] patch, which you Acked. Greg was trying to solve the problem of not having to enable ARCH_EXYNOS on kernels which are designed to be platform agnostic (sometimes called Generic Kernels). For some reason SERIAL_SAMSUNG is the only symbol with these dependencies, so the solution seemed simple and straight forward at the time.

Quoted 6 lines

However, For sound reasons Geert NACKed the patch.

Quoting from [1] he says:

"A generic kernel will include Samsung SoC support, hence PLAT_SAMSUNG or ARCH_EXYNOS will be enabled."

Yes, it's correct reasoning. There is also one more use-case - non-upstreamed (out of tree) platform which wants to use Exynos-specific drivers. Something like was happening with Apple M1 except that it got upstreamed and we do not care much about out-of-tree.

Quoted 5 lines

However, since the entry for ARCH_EXYNOS *insists* on building-in a bunch of other symbols (via 'select') which will be unused in most cases, this is not a currently acceptable approach for many Generic Kernels due to size constraints.

In the mainline kernel there is no such use case. If you want to have Exynos-whatever-driver (e.g. SERIAL_SAMSUNG or S3C RTC), you should select ARCH_EXYNOS because otherwise it does not make any sense. Zero sense. Such kernel won't work.

It makes sense only if there is some other work, hidden here, where someone might want to have SERIAL_SAMSUNG or S3C RTC without ARCH_EXYNOS. Although GKI is not that work because GKI kernel will select ARCH_EXYNOS. It must select ARCH_EXYNOS if it wants to support Exynos platforms.

Therefore I expect first to bring this "some other work, hidden here" to broader audience, so we can review its use case.

Quoted 5 lines

What this patch does is migrates those symbols from being 'select'ed (always built-in with no recourse) to 'default y'. Where the former cannot be over-ridden, but the latter can be via a vendor's defconfig/fragment.

It cannot be overridden by vendor fragment because options are not visible. You cannot change them.

The patch does nothing in this regard (making them selectable/possible to disable), which is why I complained.

Quoted 1 line

Quoted 7 lines

Quoted 3 lines

I doubt many (any?) of these symbols can be converted to kernel modules anyway, as they are required very early on in the boot sequence.

True, some could, some not. Also some platforms are set up via bootloader, so actually could "survive" till module is loaded from some initrd.

Hi Krzysztof,

I was trying to chime in, but the discussion got spread out across all the patches. Since the cover letter seems to have everyone, I thought I'd reply here. Hope you don't mind. I'll try to respond/chime in on the various topics that were raised across the patches.

Yes, the next patch series would To/Cc folks correctly. William simply forgot to use the --to-cover and --cc-cover options when using git send-email.

I agree with you that it doesn't make sense to have ARCH_EXYNOS enabled but to have all the clock drivers exynos compiled out. Then one obviously can't boot an exynos platform using that kernel.

I think
William is going to send out a new patch series with a few drivers modularized. That'll ensure all the common exynos clock code is modularized and we have a few examples of exynos clock modules.

Speaking of modules, a fully modularized generic ARM64 kernel where everything is modularized out and we only load the necessary modules is a great goal. And this is where I can chime in the most since I wrote fw_devlink and tested this out. Such a kernel is not hypothetical. IIRC hikey960 can already do this. There's an upstream amlogic(?) board that can do this (Kevin Hilman has done that). A more complex/recent/powerful, but downstream example is the Pixel 5 -- it has a fully modular kernel. 320+ modules! Including interrupt controllers, timers, pinctrl and clocks.

I can assure you any of the framework code related to pulling off booting a fully modular ARM64 kernel is already upstreamed (fw_devlink, irq framework changes, etc) or sent upstream (timer -- by a SoC vendor, etc) and being worked on. As for fw_devlink, I've extended it way past what GKI or Android would need. It would have been super trivial if all I wanted to do was support Android devices. I've also upstreamed changes that improve module loading time for all ARM64 modules. All of this and more upstream work came out of GKI and our push to be upstream first -- so I think it's reasonable to say the GKI effort helps and cares to get more work upstreamed.

Speaking of GKI, let's not speak of it. It really doesn't matter. Android is just yet another distribution (albeit a very popular one). The part that's relevant to upstream/all the other distributions is the fully modular generic ARM64 kernel and that's what we should focus on.

In that context, I think William's attempts are reasonable and I think he'll be glad to fix up any technical issues that people point out. So hopefully we can focus on that?

Quoted 85 lines · Saravana Kannan

Quoted 66 lines · Krzysztof Kozlowski

Quoted 23 lines · Lee Jones

Quoted 11 lines · Krzysztof Kozlowski

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

The wording is unfortunate. The reason for this change doesn't have much to do with kernel modules.

Let's go back in time 18 months or so when Greg KH submitted this [0] patch, which you Acked. Greg was trying to solve the problem of not having to enable ARCH_EXYNOS on kernels which are designed to be platform agnostic (sometimes called Generic Kernels). For some reason SERIAL_SAMSUNG is the only symbol with these dependencies, so the solution seemed simple and straight forward at the time.

Quoted 6 lines

However, For sound reasons Geert NACKed the patch.

Quoting from [1] he says:

"A generic kernel will include Samsung SoC support, hence PLAT_SAMSUNG or ARCH_EXYNOS will be enabled."

Yes, it's correct reasoning. There is also one more use-case - non-upstreamed (out of tree) platform which wants to use Exynos-specific drivers. Something like was happening with Apple M1 except that it got upstreamed and we do not care much about out-of-tree.

Quoted 4 lines

However, since the entry for ARCH_EXYNOS *insists* on building-in a bunch of other symbols (via 'select') which will be unused in most cases, this is not a currently acceptable approach for many Generic Kernels due to size constraints.

In the mainline kernel there is no such use case. If you want to have Exynos-whatever-driver (e.g. SERIAL_SAMSUNG or S3C RTC), you should select ARCH_EXYNOS because otherwise it does not make any sense. Zero sense. Such kernel won't work.

It makes sense only if there is some other work, hidden here, where someone might want to have SERIAL_SAMSUNG or S3C RTC without ARCH_EXYNOS. Although GKI is not that work because GKI kernel will select ARCH_EXYNOS. It must select ARCH_EXYNOS if it wants to support Exynos platforms.

Therefore I expect first to bring this "some other work, hidden here" to broader audience, so we can review its use case.

Quoted 4 lines

What this patch does is migrates those symbols from being 'select'ed (always built-in with no recourse) to 'default y'. Where the former cannot be over-ridden, but the latter can be via a vendor's defconfig/fragment.

It cannot be overridden by vendor fragment because options are not visible. You cannot change them.

The patch does nothing in this regard (making them selectable/possible to disable), which is why I complained.

Quoted 7 lines

Quoted 3 lines

I doubt many (any?) of these symbols can be converted to kernel modules anyway, as they are required very early on in the boot sequence.

True, some could, some not. Also some platforms are set up via bootloader, so actually could "survive" till module is loaded from some initrd.

I was trying to chime in, but the discussion got spread out across all the patches. Since the cover letter seems to have everyone, I thought I'd reply here. Hope you don't mind. I'll try to respond/chime in on the various topics that were raised across the patches.

Yes, the next patch series would To/Cc folks correctly. William simply forgot to use the --to-cover and --cc-cover options when using git send-email.

Quoted 3 lines

I agree with you that it doesn't make sense to have ARCH_EXYNOS enabled but to have all the clock drivers exynos compiled out. Then one obviously can't boot an exynos platform using that kernel.

If downstream kernel does not use any upstream platforms (e.g. Exynos5433 or Exynos7) and has its own drivers for everything, then downstream does not even need ARCH_EXYNOS. Just disable it.

Quoted 92 lines · Saravana Kannan

Quoted 71 lines · Krzysztof Kozlowski

Quoted 24 lines · Lee Jones

Quoted 11 lines · Krzysztof Kozlowski

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

The wording is unfortunate. The reason for this change doesn't have much to do with kernel modules.

Let's go back in time 18 months or so when Greg KH submitted this [0] patch, which you Acked. Greg was trying to solve the problem of not having to enable ARCH_EXYNOS on kernels which are designed to be platform agnostic (sometimes called Generic Kernels). For some reason SERIAL_SAMSUNG is the only symbol with these dependencies, so the solution seemed simple and straight forward at the time.

Quoted 6 lines

However, For sound reasons Geert NACKed the patch.

Quoting from [1] he says:

"A generic kernel will include Samsung SoC support, hence PLAT_SAMSUNG or ARCH_EXYNOS will be enabled."

Yes, it's correct reasoning. There is also one more use-case - non-upstreamed (out of tree) platform which wants to use Exynos-specific drivers. Something like was happening with Apple M1 except that it got upstreamed and we do not care much about out-of-tree.

Quoted 5 lines

However, since the entry for ARCH_EXYNOS *insists* on building-in a bunch of other symbols (via 'select') which will be unused in most cases, this is not a currently acceptable approach for many Generic Kernels due to size constraints.

In the mainline kernel there is no such use case. If you want to have Exynos-whatever-driver (e.g. SERIAL_SAMSUNG or S3C RTC), you should select ARCH_EXYNOS because otherwise it does not make any sense. Zero sense. Such kernel won't work.

It makes sense only if there is some other work, hidden here, where someone might want to have SERIAL_SAMSUNG or S3C RTC without ARCH_EXYNOS. Although GKI is not that work because GKI kernel will select ARCH_EXYNOS. It must select ARCH_EXYNOS if it wants to support Exynos platforms.

Therefore I expect first to bring this "some other work, hidden here" to broader audience, so we can review its use case.

Quoted 5 lines

What this patch does is migrates those symbols from being 'select'ed (always built-in with no recourse) to 'default y'. Where the former cannot be over-ridden, but the latter can be via a vendor's defconfig/fragment.

It cannot be overridden by vendor fragment because options are not visible. You cannot change them.

The patch does nothing in this regard (making them selectable/possible to disable), which is why I complained.

Quoted 1 line

Quoted 7 lines

Quoted 3 lines

I doubt many (any?) of these symbols can be converted to kernel modules anyway, as they are required very early on in the boot sequence.

True, some could, some not. Also some platforms are set up via bootloader, so actually could "survive" till module is loaded from some initrd.

Hi Krzysztof,

I was trying to chime in, but the discussion got spread out across all the patches. Since the cover letter seems to have everyone, I thought I'd reply here. Hope you don't mind. I'll try to respond/chime in on the various topics that were raised across the patches.

Yes, the next patch series would To/Cc folks correctly. William simply forgot to use the --to-cover and --cc-cover options when using git send-email.

Quoted 3 lines

I agree with you that it doesn't make sense to have ARCH_EXYNOS enabled but to have all the clock drivers exynos compiled out. Then one obviously can't boot an exynos platform using that kernel.

If downstream kernel does not use any upstream platforms (e.g. Exynos5433 or Exynos7) and has its own drivers for everything, then downstream does not even need ARCH_EXYNOS. Just disable it.

Quoted 4 lines

I think
William is going to send out a new patch series with a few drivers modularized. That'll ensure all the common exynos clock code is modularized and we have a few examples of exynos clock modules.

If it works on supported Exynos platforms: awesome!

If it does not work: not that good. I understand that downstream or vendor do not want to mainline their SoC drivers and SoC support. Either because HW is too new (do not disclose it) or it is too old (lost interest). It's their right, they do not have to work with mainline on this. However changing mainline kernel in such a case to affect it so you can use your non-upstreamed drivers is wrong.

Affecting upstream platforms just because vendor/downstream does not want to mainline some code is unacceptable. Please upstream your drivers and DTS.

Everyone else are working like this. NXP, Renesas, Xilinx, TI, Rockchip, AllWinner. Samsung or Google is not special to receive an exception for this.

Quoted 10 lines

Speaking of modules, a fully modularized generic ARM64 kernel where everything is modularized out and we only load the necessary modules is a great goal. And this is where I can chime in the most since I wrote fw_devlink and tested this out. Such a kernel is not hypothetical. IIRC hikey960 can already do this. There's an upstream amlogic(?) board that can do this (Kevin Hilman has done that). A more complex/recent/powerful, but downstream example is the Pixel 5 -- it has a fully modular kernel. 320+ modules! Including interrupt controllers, timers, pinctrl and clocks.

Awesome! I am in, if it works. :)

Quoted 10 lines

I can assure you any of the framework code related to pulling off booting a fully modular ARM64 kernel is already upstreamed (fw_devlink, irq framework changes, etc) or sent upstream (timer -- by a SoC vendor, etc) and being worked on. As for fw_devlink, I've extended it way past what GKI or Android would need. It would have been super trivial if all I wanted to do was support Android devices. I've also upstreamed changes that improve module loading time for all ARM64 modules. All of this and more upstream work came out of GKI and our push to be upstream first -- so I think it's reasonable to say the GKI effort helps and cares to get more work upstreamed.

Except UFS driver and recent Linaro work on Exynos850, none of these apply to the vendor discussed here.

Quoted 9 lines

Speaking of GKI, let's not speak of it. It really doesn't matter. Android is just yet another distribution (albeit a very popular one). The part that's relevant to upstream/all the other distributions is the fully modular generic ARM64 kernel and that's what we should focus on.

In that context, I think William's attempts are reasonable and I think he'll be glad to fix up any technical issues that people point out. So hopefully we can focus on that?

Yes, we can focus on that.

In technical issues, I do not agree to
affecting negatively supported platforms just because downstream/vendor does not want to send upstream its drivers.

Please upstream your drivers. By "your" I mean all the drivers which you want to enable after disabling ARCH_EXYNOS mainline drivers.

Quoted 93 lines · Krzysztof Kozlowski

Quoted 91 lines · Saravana Kannan

Quoted 69 lines · Krzysztof Kozlowski

Quoted 23 lines · Lee Jones

Quoted 11 lines · Krzysztof Kozlowski

Quoted 7 lines · Will McVicker

This patch series tries to address the issue of ARCH_EXYNOS force selecting a handful of drivers without allowing the vendor to override any of the default configs. This takes away from the flexibilty of compiling a generic kernel with exynos kernel modules. For example, it doesn't allow vendors to modularize these drivers out of the core kernel in order to share a generic kernel image across multiple devices that require device-specific kernel modules.

You do not address the issue in these patches. The problem you describe is that drivers are not modules and you are not changing them into modules.

The wording is unfortunate. The reason for this change doesn't have much to do with kernel modules.

Let's go back in time 18 months or so when Greg KH submitted this [0] patch, which you Acked. Greg was trying to solve the problem of not having to enable ARCH_EXYNOS on kernels which are designed to be platform agnostic (sometimes called Generic Kernels). For some reason SERIAL_SAMSUNG is the only symbol with these dependencies, so the solution seemed simple and straight forward at the time.

Quoted 6 lines

However, For sound reasons Geert NACKed the patch.

Quoting from [1] he says:

"A generic kernel will include Samsung SoC support, hence PLAT_SAMSUNG or ARCH_EXYNOS will be enabled."

Yes, it's correct reasoning. There is also one more use-case - non-upstreamed (out of tree) platform which wants to use Exynos-specific drivers. Something like was happening with Apple M1 except that it got upstreamed and we do not care much about out-of-tree.

Quoted 5 lines

However, since the entry for ARCH_EXYNOS *insists* on building-in a bunch of other symbols (via 'select') which will be unused in most cases, this is not a currently acceptable approach for many Generic Kernels due to size constraints.

In the mainline kernel there is no such use case. If you want to have Exynos-whatever-driver (e.g. SERIAL_SAMSUNG or S3C RTC), you should select ARCH_EXYNOS because otherwise it does not make any sense. Zero sense. Such kernel won't work.

It makes sense only if there is some other work, hidden here, where someone might want to have SERIAL_SAMSUNG or S3C RTC without ARCH_EXYNOS. Although GKI is not that work because GKI kernel will select ARCH_EXYNOS. It must select ARCH_EXYNOS if it wants to support Exynos platforms.

Therefore I expect first to bring this "some other work, hidden here" to broader audience, so we can review its use case.

Quoted 5 lines

What this patch does is migrates those symbols from being 'select'ed (always built-in with no recourse) to 'default y'. Where the former cannot be over-ridden, but the latter can be via a vendor's defconfig/fragment.

It cannot be overridden by vendor fragment because options are not visible. You cannot change them.

The patch does nothing in this regard (making them selectable/possible to disable), which is why I complained.

Quoted 1 line

Quoted 7 lines

Quoted 3 lines

I doubt many (any?) of these symbols can be converted to kernel modules anyway, as they are required very early on in the boot sequence.

True, some could, some not. Also some platforms are set up via bootloader, so actually could "survive" till module is loaded from some initrd.

I was trying to chime in, but the discussion got spread out across all the patches. Since the cover letter seems to have everyone, I thought I'd reply here. Hope you don't mind. I'll try to respond/chime in on the various topics that were raised across the patches.

Yes, the next patch series would To/Cc folks correctly. William simply forgot to use the --to-cover and --cc-cover options when using git send-email.

I agree with you that it doesn't make sense to have ARCH_EXYNOS enabled but to have all the clock drivers exynos compiled out. Then one obviously can't boot an exynos platform using that kernel.

Quoted 3 lines

If downstream kernel does not use any upstream platforms (e.g. Exynos5433 or Exynos7) and has its own drivers for everything, then downstream does not even need ARCH_EXYNOS. Just disable it.

As Geert pointed out in another reply, that prevents the use of earlyconsole on an exynos SoC + fully modular generic kernel. Are we okay with removing the ARCH_EXYNOS dependency on the early console driver now?