clk: exynos5420: Keep aclk66_peric enabled during boot

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

---
 drivers/clk/samsung/clk-exynos5420.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

drivers/clk/samsung/clk-exynos5420.c +6 -0

index 9d7d7ee..1e586be 100644
@@ -1172,11 +1172,17 @@ static struct of_device_id ext_clk_match[] __initdata = {
        { },
 };
 
+/* Keep these clocks on until late_initcall */
+static const char *boot_clocks[] __initconst = {
+       "aclk66_peric",
+};
+
 /* register exynos5420 clocks */
 static void __init exynos5x_clk_init(struct device_node *np,
                enum exynos5x_soc soc)
 {
        struct samsung_clk_provider *ctx;
+       int i;
 
        if (np) {
                reg_base = of_iomap(np, 0);

drivers/clk/samsung/clk-exynos5420.c +3 -0

+
+               clk_prepare_enable(to_enable);
+       }
 }
 
 static void __init exynos5420_clk_init(struct device_node *np)

@@ -1239,3 +1251,15 @@ static void __init exynos5800_clk_init(struct device_node *np)
        exynos5x_clk_init(np, EXYNOS5800);
 }

drivers/clk/samsung/clk-exynos5420.c +3 -0

+       }
+}
+late_initcall(exynos5420_clk_late_init);

Signature · 1 line

1.9.1.423.g4596e3a

Quoting Doug Anderson (2014-05-29 14:21:36)

Quoted 47 lines

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

---
 drivers/clk/samsung/clk-exynos5420.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

drivers/clk/samsung/clk-exynos5420.c +6 -0

index 9d7d7ee..1e586be 100644
@@ -1172,11 +1172,17 @@ static struct of_device_id ext_clk_match[] __initdata = {
        { },
 };
 
+/* Keep these clocks on until late_initcall */
+static const char *boot_clocks[] __initconst = {
+       "aclk66_peric",
+};
+
 /* register exynos5420 clocks */
 static void __init exynos5x_clk_init(struct device_node *np,
                enum exynos5x_soc soc)
 {
        struct samsung_clk_provider *ctx;
+       int i;
 
        if (np) {
                reg_base = of_iomap(np, 0);

@@ -1226,6 +1232,12 @@ static void __init exynos5x_clk_init(struct device_node *np,
        }
 

drivers/clk/samsung/clk-exynos5420.c static void __init exynos5x_clk_init(struct device_node *np, · line 1237

Quoted 4 lines

drivers/clk/samsung/clk-exynos5420.c +3 -0

        exynos5420_clk_sleep_init();
+
+       for (i = 0; i < ARRAY_SIZE(boot_clocks); i++) {
+               struct clk *to_enable = __clk_lookup(boot_clocks[i]);

How about replacing __clk_lookup with clk_get? You can keep the struct clk object hanging around for later...

Hi,

Quoted 48 lines · Mike Turquette

Quoting Doug Anderson (2014-05-29 14:21:36)

Quoted 47 lines

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

---
 drivers/clk/samsung/clk-exynos5420.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

drivers/clk/samsung/clk-exynos5420.c +6 -0

index 9d7d7ee..1e586be 100644
@@ -1172,11 +1172,17 @@ static struct of_device_id ext_clk_match[] __initdata = {
        { },
 };
 
+/* Keep these clocks on until late_initcall */
+static const char *boot_clocks[] __initconst = {
+       "aclk66_peric",
+};
+
 /* register exynos5420 clocks */
 static void __init exynos5x_clk_init(struct device_node *np,
                enum exynos5x_soc soc)
 {
        struct samsung_clk_provider *ctx;
+       int i;
 
        if (np) {
                reg_base = of_iomap(np, 0);

@@ -1226,6 +1232,12 @@ static void __init exynos5x_clk_init(struct device_node *np,
        }
 

Quoted 8 lines

drivers/clk/samsung/clk-exynos5420.c static void __init exynos5x_clk_init(struct device_node *np, · line 1237

Quoted 4 lines

drivers/clk/samsung/clk-exynos5420.c +3 -0

        exynos5420_clk_sleep_init();
+
+       for (i = 0; i < ARRAY_SIZE(boot_clocks); i++) {
+               struct clk *to_enable = __clk_lookup(boot_clocks[i]);

How about replacing __clk_lookup with clk_get? You can keep the struct clk object hanging around for later...

Mike, correct me if I'm wrong, but I thought you need clkdev look-up entry for clk_get() to find a clock. Here, this clock apparently don't have one and you don't even have a struct device * to pass to clk_get(), so even if you had a look-up entry, it would need to be a wildcard entry (with NULL device), which wouldn't be too elegant.

Doug, isn't a similar thing needed for PM debug as well? Maybe having this clock always ungated whenever DEBUG_LL is enabled would be enough?

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

---
 drivers/clk/samsung/clk-exynos5420.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

drivers/clk/samsung/clk-exynos5420.c +14 -0

index 9d7d7ee..1e586be 100644
@@ -1172,11 +1172,17 @@ static struct of_device_id ext_clk_match[] __initdata = {
 	{ },
 };
 
+/* Keep these clocks on until late_initcall */
+static const char *boot_clocks[] __initconst = {
+	"aclk66_peric",
+};
+
 /* register exynos5420 clocks */
 static void __init exynos5x_clk_init(struct device_node *np,
 		enum exynos5x_soc soc)
 {
 	struct samsung_clk_provider *ctx;
+	int i;
 
 	if (np) {
 		reg_base = of_iomap(np, 0);

@@ -1226,6 +1232,12 @@ static void __init exynos5x_clk_init(struct device_node *np,
 	}
 
 	exynos5420_clk_sleep_init();
+
+	for (i = 0; i < ARRAY_SIZE(boot_clocks); i++) {
+		struct clk *to_enable = __clk_lookup(boot_clocks[i]);
+
+		clk_prepare_enable(to_enable);
+	}
 }
 
 static void __init exynos5420_clk_init(struct device_node *np)

@@ -1239,3 +1251,15 @@ static void __init exynos5800_clk_init(struct device_node *np)
 	exynos5x_clk_init(np, EXYNOS5800);
 }
 CLK_OF_DECLARE(exynos5800_clk, "samsung,exynos5800-clock", exynos5800_clk_init);
+
+static int __init exynos5420_clk_late_init(void)

Quoted 11 lines

drivers/clk/samsung/clk-exynos5420.c +7 -0

@@ -1239,3 +1251,15 @@ static void __init exynos5800_clk_init(struct device_node *np)
      exynos5x_clk_init(np, EXYNOS5800);
 }
 CLK_OF_DECLARE(exynos5800_clk, "samsung,exynos5800-clock", exynos5800_clk_init);
+
+static int __init exynos5420_clk_late_init(void)
+{
+     int i;
+
+     for (i = 0; i < ARRAY_SIZE(boot_clocks); i++) {
+             struct clk *to_disable = __clk_lookup(boot_clocks[i]);

drivers/clk/samsung/clk-exynos5420.c static void __init exynos5800_clk_init(struct device_node *np) · line 1265

Quoted 6 lines

drivers/clk/samsung/clk-exynos5420.c +5 -0

+
+             clk_disable_unprepare(to_disable);
+     }
+}
+late_initcall(exynos5420_clk_late_init);

You should return 0 here.

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

Tested-by Javier Martinez Canillas <[email protected]>

---
Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

Tomasz / Mike,

Quoted 24 lines · Doug Anderson

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

Tested-by Javier Martinez Canillas <[email protected]>

---
Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

Quoted 2 lines

 drivers/clk/samsung/clk-exynos5420.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

Are there other changes you'd like me to make to this? It would be really nice to get this in for 3.16 so the system doesn't just mysteriously hang when you use earlyprintk.

Quoted 30 lines · Doug Anderson

Tomasz / Mike,

Quoted 26 lines · Doug Anderson

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

Tested-by Javier Martinez Canillas <[email protected]>

---
Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

Quoted 3 lines

Are there other changes you'd like me to make to this? It would be really nice to get this in for 3.16 so the system doesn't just mysteriously hang when you use earlyprintk.

We can probably take this as an -rc fix, so it should be fine.

However I still don't see the point of exporting this clock and polluting the global clkdev namespace. Even the diffstat looks better in v1.

Tomasz,

Quoted 35 lines · Tomasz Figa

Quoted 33 lines · Doug Anderson

Tomasz / Mike,

Quoted 19 lines · Doug Anderson

Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:

1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2".
2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design).
3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang.

There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver.

Signed-off-by Doug Anderson <[email protected]>

Tested-by Javier Martinez Canillas <[email protected]>

Quoted 7 lines

---
Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

Are there other changes you'd like me to make to this? It would be really nice to get this in for 3.16 so the system doesn't just mysteriously hang when you use earlyprintk.

Quoted 4 lines

We can probably take this as an -rc fix, so it should be fine.

However I still don't see the point of exporting this clock and polluting the global clkdev namespace. Even the diffstat looks better in v1.

OK, I'm happy to go back to v1 with the addition of the "return 0".

Mike: are you OK with that?

One more question that just came to my mind: Why it is just the aclk66_peri and not its children related to UARTs?

Exynos5420 clock driver still needs a little clean-up, so I'm okay with any fix for now and changing this later if needed, but is this gate clock for ACLK66_PERIC even needed? It seems to be marked with CLK_IGNORE_UNUSED which suggests that it is not needed in this driver at all, along with other similar clocks. AFAIK for power management purposes our fine-grained approach is fine and we shouldn't need to use the big gates.

Hmmm, I think I've convinced myself that your suggestion of just removing this gate from the table is the right thing to do. Patch will be coming up soon.

The "aclk66_peric" clock is a gate clock with a whole bunch of gates underneath it. This big gate isn't very useful to include in our clock tree. If any of the children need to be turned on then the big gate will need to be on anyway. ...and there are plenty of other "big gates" that aren't described in our clock tree, some of which shut off collections of clocks that have no relationship in the hierarchy so are hard to model.

"aclk66_peric" is causing earlyprintk problems since it gets disabled as part of the boot process, so let's just remove it.

Strangely (and for no good reason) this clock is exported as part of the common clock bindings. Remove it since there are no in-kernel device trees using it and no reason anyone out of tree should refer to it either.

Signed-off-by Doug Anderson <[email protected]>

---
Changes in v3:
- Now just remove aclk66_peric from the tree as suggested by Tomasz.

Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c   | 85 ++++++++++++++++++++++------------
 include/dt-bindings/clock/exynos5420.h |  1 -
 2 files changed, 55 insertions(+), 31 deletions(-)

Quoted 21 lines

The "aclk66_peric" clock is a gate clock with a whole bunch of gates underneath it. This big gate isn't very useful to include in our clock tree. If any of the children need to be turned on then the big gate will need to be on anyway. ...and there are plenty of other "big gates" that aren't described in our clock tree, some of which shut off collections of clocks that have no relationship in the hierarchy so are hard to model.

"aclk66_peric" is causing earlyprintk problems since it gets disabled as part of the boot process, so let's just remove it.

Strangely (and for no good reason) this clock is exported as part of the common clock bindings. Remove it since there are no in-kernel device trees using it and no reason anyone out of tree should refer to it either.

Signed-off-by Doug Anderson <[email protected]>

---
Changes in v3:
- Now just remove aclk66_peric from the tree as suggested by Tomasz.

Quoted 8 lines

Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c   | 85 ++++++++++++++++++++++------------
 include/dt-bindings/clock/exynos5420.h |  1 -
 2 files changed, 55 insertions(+), 31 deletions(-)

Mike, I can take this patch to my tree as a fix for 3.16-rc, or if still possible and you don't mind, feel free to apply it directly with my ACK:

Acked-by Tomasz Figa <[email protected]>

Best regards,
Tomasz

Quoting Tomasz Figa (2014-06-05 15:26:31)

Quoted 31 lines · Doug Anderson

Quoted 29 lines

The "aclk66_peric" clock is a gate clock with a whole bunch of gates underneath it. This big gate isn't very useful to include in our clock tree. If any of the children need to be turned on then the big gate will need to be on anyway. ...and there are plenty of other "big gates" that aren't described in our clock tree, some of which shut off collections of clocks that have no relationship in the hierarchy so are hard to model.

"aclk66_peric" is causing earlyprintk problems since it gets disabled as part of the boot process, so let's just remove it.

Strangely (and for no good reason) this clock is exported as part of the common clock bindings. Remove it since there are no in-kernel device trees using it and no reason anyone out of tree should refer to it either.

Signed-off-by Doug Anderson <[email protected]>

---
Changes in v3:
- Now just remove aclk66_peric from the tree as suggested by Tomasz.

Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c   | 85 ++++++++++++++++++++++------------
 include/dt-bindings/clock/exynos5420.h |  1 -
 2 files changed, 55 insertions(+), 31 deletions(-)

Quoted 4 lines

Mike, I can take this patch to my tree as a fix for 3.16-rc, or if still possible and you don't mind, feel free to apply it directly with my ACK:

Acked-by Tomasz Figa <[email protected]>

I'll send a second PR next week that includes this.

The "aclk66_peric" clock is a gate clock with a whole bunch of gates underneath it. This big gate isn't very useful to include in our clock tree. If any of the children need to be turned on then the big gate will need to be on anyway. ...and there are plenty of other "big gates" that aren't described in our clock tree, some of which shut off collections of clocks that have no relationship in the hierarchy so are hard to model.

"aclk66_peric" is causing earlyprintk problems since it gets disabled as part of the boot process, so let's just remove it.

Strangely (and for no good reason) this clock is exported as part of the common clock bindings. Remove it since there are no in-kernel device trees using it and no reason anyone out of tree should refer to it either.

Signed-off-by Doug Anderson <[email protected]>

---
Changes in v3:
- Now just remove aclk66_peric from the tree as suggested by Tomasz.

Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c   | 85 ++++++++++++++++++++++------------
 include/dt-bindings/clock/exynos5420.h |  1 -
 2 files changed, 55 insertions(+), 31 deletions(-)

drivers/clk/samsung/clk-exynos5420.c +55 -30

index 9d7d7ee..61eccf0 100644
@@ -890,8 +890,6 @@ static struct samsung_gate_clock exynos5x_gate_clks[] __initdata = {
                        GATE_BUS_TOP, 9, CLK_IGNORE_UNUSED, 0),
        GATE(0, "aclk66_psgen", "mout_user_aclk66_psgen",
                        GATE_BUS_TOP, 10, CLK_IGNORE_UNUSED, 0),
-       GATE(CLK_ACLK66_PERIC, "aclk66_peric", "mout_user_aclk66_peric",
-                       GATE_BUS_TOP, 11, CLK_IGNORE_UNUSED, 0),
        GATE(0, "aclk266_isp", "mout_user_aclk266_isp",
                        GATE_BUS_TOP, 13, 0, 0),
        GATE(0, "aclk166", "mout_user_aclk166",

@@ -994,34 +992,61 @@ static struct samsung_gate_clock exynos5x_gate_clks[] __initdata = {
                        SRC_MASK_FSYS, 24, CLK_SET_RATE_PARENT, 0),
 
        /* PERIC Block */
-       GATE(CLK_UART0, "uart0", "aclk66_peric", GATE_IP_PERIC, 0, 0, 0),
-       GATE(CLK_UART1, "uart1", "aclk66_peric", GATE_IP_PERIC, 1, 0, 0),
-       GATE(CLK_UART2, "uart2", "aclk66_peric", GATE_IP_PERIC, 2, 0, 0),
-       GATE(CLK_UART3, "uart3", "aclk66_peric", GATE_IP_PERIC, 3, 0, 0),
-       GATE(CLK_I2C0, "i2c0", "aclk66_peric", GATE_IP_PERIC, 6, 0, 0),
-       GATE(CLK_I2C1, "i2c1", "aclk66_peric", GATE_IP_PERIC, 7, 0, 0),
-       GATE(CLK_I2C2, "i2c2", "aclk66_peric", GATE_IP_PERIC, 8, 0, 0),
-       GATE(CLK_I2C3, "i2c3", "aclk66_peric", GATE_IP_PERIC, 9, 0, 0),
-       GATE(CLK_USI0, "usi0", "aclk66_peric", GATE_IP_PERIC, 10, 0, 0),
-       GATE(CLK_USI1, "usi1", "aclk66_peric", GATE_IP_PERIC, 11, 0, 0),
-       GATE(CLK_USI2, "usi2", "aclk66_peric", GATE_IP_PERIC, 12, 0, 0),
-       GATE(CLK_USI3, "usi3", "aclk66_peric", GATE_IP_PERIC, 13, 0, 0),
-       GATE(CLK_I2C_HDMI, "i2c_hdmi", "aclk66_peric", GATE_IP_PERIC, 14, 0, 0),
-       GATE(CLK_TSADC, "tsadc", "aclk66_peric", GATE_IP_PERIC, 15, 0, 0),
-       GATE(CLK_SPI0, "spi0", "aclk66_peric", GATE_IP_PERIC, 16, 0, 0),
-       GATE(CLK_SPI1, "spi1", "aclk66_peric", GATE_IP_PERIC, 17, 0, 0),
-       GATE(CLK_SPI2, "spi2", "aclk66_peric", GATE_IP_PERIC, 18, 0, 0),
-       GATE(CLK_I2S1, "i2s1", "aclk66_peric", GATE_IP_PERIC, 20, 0, 0),
-       GATE(CLK_I2S2, "i2s2", "aclk66_peric", GATE_IP_PERIC, 21, 0, 0),
-       GATE(CLK_PCM1, "pcm1", "aclk66_peric", GATE_IP_PERIC, 22, 0, 0),
-       GATE(CLK_PCM2, "pcm2", "aclk66_peric", GATE_IP_PERIC, 23, 0, 0),
-       GATE(CLK_PWM, "pwm", "aclk66_peric", GATE_IP_PERIC, 24, 0, 0),
-       GATE(CLK_SPDIF, "spdif", "aclk66_peric", GATE_IP_PERIC, 26, 0, 0),
-       GATE(CLK_USI4, "usi4", "aclk66_peric", GATE_IP_PERIC, 28, 0, 0),
-       GATE(CLK_USI5, "usi5", "aclk66_peric", GATE_IP_PERIC, 30, 0, 0),
-       GATE(CLK_USI6, "usi6", "aclk66_peric", GATE_IP_PERIC, 31, 0, 0),
-
-       GATE(CLK_KEYIF, "keyif", "aclk66_peric", GATE_BUS_PERIC, 22, 0, 0),
+       GATE(CLK_UART0, "uart0", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 0, 0, 0),
+       GATE(CLK_UART1, "uart1", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 1, 0, 0),
+       GATE(CLK_UART2, "uart2", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 2, 0, 0),
+       GATE(CLK_UART3, "uart3", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 3, 0, 0),
+       GATE(CLK_I2C0, "i2c0", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 6, 0, 0),
+       GATE(CLK_I2C1, "i2c1", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 7, 0, 0),
+       GATE(CLK_I2C2, "i2c2", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 8, 0, 0),
+       GATE(CLK_I2C3, "i2c3", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 9, 0, 0),
+       GATE(CLK_USI0, "usi0", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 10, 0, 0),
+       GATE(CLK_USI1, "usi1", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 11, 0, 0),
+       GATE(CLK_USI2, "usi2", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 12, 0, 0),
+       GATE(CLK_USI3, "usi3", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 13, 0, 0),
+       GATE(CLK_I2C_HDMI, "i2c_hdmi", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 14, 0, 0),
+       GATE(CLK_TSADC, "tsadc", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 15, 0, 0),
+       GATE(CLK_SPI0, "spi0", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 16, 0, 0),
+       GATE(CLK_SPI1, "spi1", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 17, 0, 0),
+       GATE(CLK_SPI2, "spi2", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 18, 0, 0),
+       GATE(CLK_I2S1, "i2s1", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 20, 0, 0),
+       GATE(CLK_I2S2, "i2s2", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 21, 0, 0),
+       GATE(CLK_PCM1, "pcm1", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 22, 0, 0),
+       GATE(CLK_PCM2, "pcm2", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 23, 0, 0),
+       GATE(CLK_PWM, "pwm", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 24, 0, 0),
+       GATE(CLK_SPDIF, "spdif", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 26, 0, 0),
+       GATE(CLK_USI4, "usi4", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 28, 0, 0),
+       GATE(CLK_USI5, "usi5", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 30, 0, 0),
+       GATE(CLK_USI6, "usi6", "mout_user_aclk66_peric",
+                       GATE_IP_PERIC, 31, 0, 0),
+
+       GATE(CLK_KEYIF, "keyif", "mout_user_aclk66_peric",
+                       GATE_BUS_PERIC, 22, 0, 0),
 
        /* PERIS Block */
        GATE(CLK_CHIPID, "chipid", "aclk66_psgen",

include/dt-bindings/clock/exynos5420.h +0 -1

index 97dcb89..14e1c8f 100644
@@ -63,7 +63,6 @@
 #define CLK_SCLK_MPHY_IXTAL24  161
 
 /* gate clocks */
-#define CLK_ACLK66_PERIC       256
 #define CLK_UART0              257
 #define CLK_UART1              258
 #define CLK_UART2              259

Signature · 1 line

2.0.0.526.g5318336

Quoting Doug Anderson (2014-06-05 13:35:14)

Quoted 7 lines

The "aclk66_peric" clock is a gate clock with a whole bunch of gates underneath it. This big gate isn't very useful to include in our clock tree. If any of the children need to be turned on then the big gate will need to be on anyway. ...and there are plenty of other "big gates" that aren't described in our clock tree, some of which shut off collections of clocks that have no relationship in the hierarchy so are hard to model.

I think this is a common problem. On OMAP we have something similar to this called "clock domains" or "clkdm" and it has been historically handled outside of the Linux clock framework[1]. There is a relationship to the clock framework of course and in the future it might be worthwhile to see if there is a generic way to handle this stuff.

Quoted 7 lines

"aclk66_peric" is causing earlyprintk problems since it gets disabled as part of the boot process, so let's just remove it.

Strangely (and for no good reason) this clock is exported as part of the common clock bindings. Remove it since there are no in-kernel device trees using it and no reason anyone out of tree should refer to it either.

So Linux has no control over the big gate now, correct? You are dependent on the bootloader to ungate this thing?

Mike,

Quoted 9 lines · Mike Turquette

Quoting Doug Anderson (2014-06-05 13:35:14)

Quoted 7 lines

The "aclk66_peric" clock is a gate clock with a whole bunch of gates underneath it. This big gate isn't very useful to include in our clock tree. If any of the children need to be turned on then the big gate will need to be on anyway. ...and there are plenty of other "big gates" that aren't described in our clock tree, some of which shut off collections of clocks that have no relationship in the hierarchy so are hard to model.

Quoted 5 lines

I think this is a common problem. On OMAP we have something similar to this called "clock domains" or "clkdm" and it has been historically handled outside of the Linux clock framework[1]. There is a relationship to the clock framework of course and in the future it might be worthwhile to see if there is a generic way to handle this stuff.

That sounds like something that would be nice to solve, but it's not going to happen now.

On the off chance that the user manual mentioned the existence of one of these "big gate" bits, it tends to not be very specific about _exactly_ which sets of clocks it disables.

Tracking down every one of these would be hugely time consuming.
Also: as Tomasz has indicated they don't provide a huge amount of benefit since we're already dealing with clocks on a more fine-grained level...

Quoted 5 lines

Quoted 5 lines

"aclk66_peric" is causing earlyprintk problems since it gets disabled as part of the boot process, so let's just remove it.

Quoted 7 lines

Quoted 4 lines

Strangely (and for no good reason) this clock is exported as part of the common clock bindings. Remove it since there are no in-kernel device trees using it and no reason anyone out of tree should refer to it either.

So Linux has no control over the big gate now, correct? You are dependent on the bootloader to ungate this thing?

A better way to put it is that you're dependent on the bootloader not to gate it.

...but that's also true for pretty much any clock marked IGNORE_UNUSED and not explicitly enabled anywhere.

Are you opposed to this landing as-is to unblock things and people can continue to work on the clock driver to make it even better?

-Doug

Anyways, getting back on point, Tomasz was right about the whole clk_get thing. So I'm happy to take either V1 or V3 of your patch. I will be submitting a second PR for 3.16 next week and it will include whichever version you and Tomasz agree is best.

The "aclk66_peric" clock is a gate clock with a whole bunch of gates underneath it. This big gate isn't very useful to include in our clock tree. If any of the children need to be turned on then the big gate will need to be on anyway. ...and there are plenty of other "big gates" that aren't described in our clock tree, some of which shut off collections of clocks that have no relationship in the hierarchy so are hard to model.

"aclk66_peric" is causing earlyprintk problems since it gets disabled as part of the boot process, so let's just remove it.

Strangely (and for no good reason) this clock is exported as part of the common clock bindings. Remove it since there are no in-kernel device trees using it and no reason anyone out of tree should refer to it either.

Signed-off-by Doug Anderson <[email protected]>

---
Changes in v3:
- Now just remove aclk66_peric from the tree as suggested by Tomasz.

Changes in v2:
- Use GATE_A and clk_get(). Save the clock for putting later.
- Return 0 from exynos5420_clk_late_init().

 drivers/clk/samsung/clk-exynos5420.c   | 85 ++++++++++++++++++++++------------
 include/dt-bindings/clock/exynos5420.h |  1 -
 2 files changed, 55 insertions(+), 31 deletions(-)