fw_devlink on will break all snps,dw-apb-gpio users

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
       compatible = "snps,dw-apb-gpio";
       #address-cells = <1>;
       #size-cells = <0>;

       porta: gpio-port@0 {
              compatible = "snps,dw-apb-gpio-port";
              gpio-controller;
              #gpio-cells = <2>;
              ngpios = <32>;
              reg = <0>;
       };
};

device_foo {
        status = "okay"
        ...;
        reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

        expander3: gpio@44 {
                compatible = "fcs,fxl6408";
                pinctrl-names = "default";
                pinctrl-0 = <&expander3_pmux>;
                reg = <0x44>;
                gpio-controller;
                #gpio-cells = <2>;
                interrupt-parent = <&portb>;
                interrupts = <23 IRQ_TYPE_NONE>;
                interrupt-controller;
                #interrupt-cells = <2>;
        };

The common pattern looks like the devlink can't cope with suppliers from child dt node.

CAUTION: Email originated externally, do not click links or open attachments unless you recognize the sender and know the content is safe.

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
       compatible = "snps,dw-apb-gpio";
       #address-cells = <1>;
       #size-cells = <0>;

       porta: gpio-port@0 {
              compatible = "snps,dw-apb-gpio-port";
              gpio-controller;
              #gpio-cells = <2>;
              ngpios = <32>;
              reg = <0>;
       };
};

device_foo {
        status = "okay"
        ...;
        reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

        expander3: gpio@44 {
                compatible = "fcs,fxl6408";
                pinctrl-names = "default";
                pinctrl-0 = <&expander3_pmux>;
                reg = <0x44>;
                gpio-controller;
                #gpio-cells = <2>;
                interrupt-parent = <&portb>;
                interrupts = <23 IRQ_TYPE_NONE>;
                interrupt-controller;
                #interrupt-cells = <2>;
        };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Quoted 62 lines · On Wed, 14 Oct 2020 10:29:36 -0700 Saravana Kannan <[email protected]> wrote:

CAUTION: Email originated externally, do not click links or open attachments unless you recognize the sender and know the content is safe.

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
       compatible = "snps,dw-apb-gpio";
       #address-cells = <1>;
       #size-cells = <0>;

       porta: gpio-port@0 {
              compatible = "snps,dw-apb-gpio-port";
              gpio-controller;
              #gpio-cells = <2>;
              ngpios = <32>;
              reg = <0>;
       };
};

device_foo {
        status = "okay"
        ...;
        reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

        expander3: gpio@44 {
                compatible = "fcs,fxl6408";
                pinctrl-names = "default";
                pinctrl-0 = <&expander3_pmux>;
                reg = <0x44>;
                gpio-controller;
                #gpio-cells = <2>;
                interrupt-parent = <&portb>;
                interrupts = <23 IRQ_TYPE_NONE>;
                interrupt-controller;
                #interrupt-cells = <2>;
        };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Quoted 6 lines

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Thanks for the information. The "snps,dw-apb-gpio-port" is never used, so I just sent out a series to remove it.

Quoted 72 lines · Jisheng Zhang

Quoted 67 lines · On Wed, 14 Oct 2020 10:29:36 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
       compatible = "snps,dw-apb-gpio";
       #address-cells = <1>;
       #size-cells = <0>;

       porta: gpio-port@0 {
              compatible = "snps,dw-apb-gpio-port";
              gpio-controller;
              #gpio-cells = <2>;
              ngpios = <32>;
              reg = <0>;
       };
};

device_foo {
        status = "okay"
        ...;
        reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

        expander3: gpio@44 {
                compatible = "fcs,fxl6408";
                pinctrl-names = "default";
                pinctrl-0 = <&expander3_pmux>;
                reg = <0x44>;
                gpio-controller;
                #gpio-cells = <2>;
                interrupt-parent = <&portb>;
                interrupts = <23 IRQ_TYPE_NONE>;
                interrupt-controller;
                #interrupt-cells = <2>;
        };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Quoted 2 lines

Thanks for the information. The "snps,dw-apb-gpio-port" is never used, so I just sent out a series to remove it.

I'd actually prefer that you fix the kernel code to actually use it. So that fw_devlink can be backward compatible (Older DT + new kernel). The change is pretty trivial (I just have time to do it for you).

Quoted 79 lines · On Wed, 14 Oct 2020 22:04:24 -0700 Saravana Kannan wrote:

Quoted 74 lines · Jisheng Zhang

Quoted 61 lines · On Wed, 14 Oct 2020 10:29:36 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
       compatible = "snps,dw-apb-gpio";
       #address-cells = <1>;
       #size-cells = <0>;

       porta: gpio-port@0 {
              compatible = "snps,dw-apb-gpio-port";
              gpio-controller;
              #gpio-cells = <2>;
              ngpios = <32>;
              reg = <0>;
       };
};

device_foo {
        status = "okay"
        ...;
        reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

        expander3: gpio@44 {
                compatible = "fcs,fxl6408";
                pinctrl-names = "default";
                pinctrl-0 = <&expander3_pmux>;
                reg = <0x44>;
                gpio-controller;
                #gpio-cells = <2>;
                interrupt-parent = <&portb>;
                interrupts = <23 IRQ_TYPE_NONE>;
                interrupt-controller;
                #interrupt-cells = <2>;
        };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Quoted 6 lines

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Thanks for the information. The "snps,dw-apb-gpio-port" is never used, so I just sent out a series to remove it.

Quoted 4 lines

I'd actually prefer that you fix the kernel code to actually use it. So that fw_devlink can be backward compatible (Older DT + new kernel). The change is pretty trivial (I just have time to do it for you).

I agree the change is trivial, but it will add some useless LoCs like below.

I'm not sure whether this is acceptable.So add GPIO and DT maintainers to comment.

Hi Linus, Rob,

Could you please comment? A simple introduction of the problem:

As pointed out by Saravana, "gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it", so once we set fw_devlink=on, then any users of gpio-dwapb as below won't be probed.

device_foo {
         status = "okay"
         ...;
         reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

The compatible string "snps,dw-apb-gpio-port" is never used, but it's in the dt-binding since the dw gpio mainlined. I believe the every dw apb users just copy the compatible string in to soc dtsi. So I submit a series to remove the unused "snps,dw-apb-gpio-port" https://lkml.org/lkml/2020/10/14/1186
But this will break Older DT + new kernel with fw_devlink on. Which solution is better?

If the following patch is acceptable, I can submit it once 5.10-rc1 is out.

thanks

drivers/gpio/gpio-dwapb.c +5 -0

index 1d8d55bd63aa..b8e012e48b59 100644
@@ -19,6 +19,7 @@
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
+#include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/reset.h>

@@ -694,6 +695,10 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
        }
        platform_set_drvdata(pdev, gpio);
 
+       err = devm_of_platform_populate(dev);
+       if (err)
+               goto out_unregister;
+
        return 0;
 
 out_unregister:

@@ -820,6 +825,25 @@ static struct platform_driver dwapb_gpio_driver = {
 

drivers/gpio/gpio-dwapb.c +11 -0

+}
+
+static struct platform_driver dwapb_gpio_port_driver = {
+       .driver         = {
+               .name   = "gpio-dwapb-port",
+               .of_match_table = dwapb_port_of_match,
+       },
+       .probe          = dwapb_gpio_port_probe,
+};
+module_platform_driver(dwapb_gpio_port_driver);
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Jamie Iles");
 MODULE_DESCRIPTION("Synopsys DesignWare APB GPIO driver");

Quoted 82 lines · Jisheng Zhang

Quoted 79 lines · On Wed, 14 Oct 2020 22:04:24 -0700 Saravana Kannan wrote:

Quoted 74 lines · Jisheng Zhang

Quoted 61 lines · On Wed, 14 Oct 2020 10:29:36 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
       compatible = "snps,dw-apb-gpio";
       #address-cells = <1>;
       #size-cells = <0>;

       porta: gpio-port@0 {
              compatible = "snps,dw-apb-gpio-port";
              gpio-controller;
              #gpio-cells = <2>;
              ngpios = <32>;
              reg = <0>;
       };
};

device_foo {
        status = "okay"
        ...;
        reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

        expander3: gpio@44 {
                compatible = "fcs,fxl6408";
                pinctrl-names = "default";
                pinctrl-0 = <&expander3_pmux>;
                reg = <0x44>;
                gpio-controller;
                #gpio-cells = <2>;
                interrupt-parent = <&portb>;
                interrupts = <23 IRQ_TYPE_NONE>;
                interrupt-controller;
                #interrupt-cells = <2>;
        };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Quoted 6 lines

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Thanks for the information. The "snps,dw-apb-gpio-port" is never used, so I just sent out a series to remove it.

Quoted 6 lines

Quoted 4 lines

I'd actually prefer that you fix the kernel code to actually use it. So that fw_devlink can be backward compatible (Older DT + new kernel). The change is pretty trivial (I just have time to do it for you).

I agree the change is trivial, but it will add some useless LoCs like below.

It's not useless if it preserves backward compatibility with DT.

Quoted 56 lines

I'm not sure whether this is acceptable.So add GPIO and DT maintainers to comment.

Hi Linus, Rob,

Could you please comment? A simple introduction of the problem:

As pointed out by Saravana, "gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it", so once we set fw_devlink=on, then any users of gpio-dwapb as below won't be probed.

device_foo {
         status = "okay"
         ...;
         reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

The compatible string "snps,dw-apb-gpio-port" is never used, but it's in the dt-binding since the dw gpio mainlined. I believe the every dw apb users just copy the compatible string in to soc dtsi. So I submit a series to remove the unused "snps,dw-apb-gpio-port" https://lkml.org/lkml/2020/10/14/1186
But this will break Older DT + new kernel with fw_devlink on. Which solution is better?

If the following patch is acceptable, I can submit it once 5.10-rc1 is out.

thanks

drivers/gpio/gpio-dwapb.c +5 -0

index 1d8d55bd63aa..b8e012e48b59 100644
@@ -19,6 +19,7 @@
 #include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
+#include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/reset.h>

@@ -694,6 +695,10 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
        }
        platform_set_drvdata(pdev, gpio);
 
+       err = devm_of_platform_populate(dev);
+       if (err)
+               goto out_unregister;
+
        return 0;
 
 out_unregister:

@@ -820,6 +825,25 @@ static struct platform_driver dwapb_gpio_driver = {
 
 module_platform_driver(dwapb_gpio_driver);
 

drivers/gpio/gpio-dwapb.c static struct platform_driver dwapb_gpio_driver = { · line 835

Quoted 8 lines

drivers/gpio/gpio-dwapb.c +8 -0

+static const struct of_device_id dwapb_port_of_match[] = {
+       { .compatible = "snps,dw-apb-gpio-port" },
+       { /* Sentinel */ }
+};
+
+static int dwapb_gpio_port_probe(struct platform_device *pdev)
+{
+       return 0;  

No, I'm not asking to do a stub/dummy probe. Move the stuff you do inside device_for_each_child_node{} and dwapb_gpio_add_port() into this probe function. Those two pieces of code together are effectively "probing" a separate gpio controller for each of the child nodes. So just create a real struct device (like we do for every other "compatible" DT node) and probe each of them properly using the device driver core.

Quoted 16 lines

drivers/gpio/gpio-dwapb.c +11 -0

+}
+
+static struct platform_driver dwapb_gpio_port_driver = {
+       .driver         = {
+               .name   = "gpio-dwapb-port",
+               .of_match_table = dwapb_port_of_match,
+       },
+       .probe          = dwapb_gpio_port_probe,
+};
+module_platform_driver(dwapb_gpio_port_driver);
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Jamie Iles");
 MODULE_DESCRIPTION("Synopsys DesignWare APB GPIO driver");

Quoted 149 lines · On Thu, 15 Oct 2020 01:48:13 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 82 lines · Jisheng Zhang

Quoted 79 lines · On Wed, 14 Oct 2020 22:04:24 -0700 Saravana Kannan wrote:

Quoted 74 lines · Jisheng Zhang

Quoted 61 lines · On Wed, 14 Oct 2020 10:29:36 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
        compatible = "snps,dw-apb-gpio";
        #address-cells = <1>;
        #size-cells = <0>;

        porta: gpio-port@0 {
               compatible = "snps,dw-apb-gpio-port";
               gpio-controller;
               #gpio-cells = <2>;
               ngpios = <32>;
               reg = <0>;
        };
};

device_foo {
         status = "okay"
         ...;
         reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

         expander3: gpio@44 {
                 compatible = "fcs,fxl6408";
                 pinctrl-names = "default";
                 pinctrl-0 = <&expander3_pmux>;
                 reg = <0x44>;
                 gpio-controller;
                 #gpio-cells = <2>;
                 interrupt-parent = <&portb>;
                 interrupts = <23 IRQ_TYPE_NONE>;
                 interrupt-controller;
                 #interrupt-cells = <2>;
         };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Quoted 6 lines

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Thanks for the information. The "snps,dw-apb-gpio-port" is never used, so I just sent out a series to remove it.

Quoted 6 lines

Quoted 4 lines

I'd actually prefer that you fix the kernel code to actually use it. So that fw_devlink can be backward compatible (Older DT + new kernel). The change is pretty trivial (I just have time to do it for you).

I agree the change is trivial, but it will add some useless LoCs like below.

It's not useless if it preserves backward compatibility with DT.

Quoted 56 lines

I'm not sure whether this is acceptable.So add GPIO and DT maintainers to comment.

Hi Linus, Rob,

Could you please comment? A simple introduction of the problem:

As pointed out by Saravana, "gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it", so once we set fw_devlink=on, then any users of gpio-dwapb as below won't be probed.

device_foo {
          status = "okay"
          ...;
          reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

The compatible string "snps,dw-apb-gpio-port" is never used, but it's in the dt-binding since the dw gpio mainlined. I believe the every dw apb users just copy the compatible string in to soc dtsi. So I submit a series to remove the unused "snps,dw-apb-gpio-port" https://lkml.org/lkml/2020/10/14/1186
But this will break Older DT + new kernel with fw_devlink on. Which solution is better?

If the following patch is acceptable, I can submit it once 5.10-rc1 is out.

thanks

drivers/gpio/gpio-dwapb.c +5 -0

index 1d8d55bd63aa..b8e012e48b59 100644
@@ -19,6 +19,7 @@
  #include <linux/of_address.h>
  #include <linux/of_device.h>
  #include <linux/of_irq.h>
+#include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/property.h>
  #include <linux/reset.h>

@@ -694,6 +695,10 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
         }
         platform_set_drvdata(pdev, gpio);
 
+       err = devm_of_platform_populate(dev);
+       if (err)
+               goto out_unregister;
+
         return 0;
 
  out_unregister:

@@ -820,6 +825,25 @@ static struct platform_driver dwapb_gpio_driver = {
 
  module_platform_driver(dwapb_gpio_driver);
 

Quoted 16 lines

drivers/gpio/gpio-dwapb.c static struct platform_driver dwapb_gpio_driver = { · line 835

Quoted 8 lines

drivers/gpio/gpio-dwapb.c +8 -0

+static const struct of_device_id dwapb_port_of_match[] = {
+       { .compatible = "snps,dw-apb-gpio-port" },
+       { /* Sentinel */ }
+};
+
+static int dwapb_gpio_port_probe(struct platform_device *pdev)
+{
+       return 0;

No, I'm not asking to do a stub/dummy probe. Move the stuff you do inside device_for_each_child_node{} and dwapb_gpio_add_port() into this probe function. Those two pieces of code together are effectively "probing" a separate gpio controller for each of the child nodes. So just create a real struct device (like we do for every other "compatible" DT node) and probe each of them properly using the device driver core.

Then I believe the modifications are non-trivial. Maybe Linus and Rob can comment which way is better, fix the dts or modify the gpio-dwapb.c. Personally, I prefer fixing dts, because this doesn't remove or modify any used properties or compatible string, it just removes the unused compatible string.

Thanks

Quoted 16 lines

Quoted 6 lines

drivers/gpio/gpio-dwapb.c +4 -0

+}
+
+static struct platform_driver dwapb_gpio_port_driver = {
+       .driver         = {

drivers/gpio/gpio-dwapb.c static struct platform_driver dwapb_gpio_driver = { · line 849

Quoted 10 lines

drivers/gpio/gpio-dwapb.c +7 -0

+               .name   = "gpio-dwapb-port",
+               .of_match_table = dwapb_port_of_match,
+       },
+       .probe          = dwapb_gpio_port_probe,
+};
+module_platform_driver(dwapb_gpio_port_driver);
+
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Jamie Iles");
  MODULE_DESCRIPTION("Synopsys DesignWare APB GPIO driver");

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Quoted 169 lines · Jisheng Zhang

Quoted 149 lines · On Thu, 15 Oct 2020 01:48:13 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 82 lines · Jisheng Zhang

Quoted 79 lines · On Wed, 14 Oct 2020 22:04:24 -0700 Saravana Kannan wrote:

Quoted 74 lines · Jisheng Zhang

Quoted 61 lines · On Wed, 14 Oct 2020 10:29:36 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
        compatible = "snps,dw-apb-gpio";
        #address-cells = <1>;
        #size-cells = <0>;

        porta: gpio-port@0 {
               compatible = "snps,dw-apb-gpio-port";
               gpio-controller;
               #gpio-cells = <2>;
               ngpios = <32>;
               reg = <0>;
        };
};

device_foo {
         status = "okay"
         ...;
         reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

         expander3: gpio@44 {
                 compatible = "fcs,fxl6408";
                 pinctrl-names = "default";
                 pinctrl-0 = <&expander3_pmux>;
                 reg = <0x44>;
                 gpio-controller;
                 #gpio-cells = <2>;
                 interrupt-parent = <&portb>;
                 interrupts = <23 IRQ_TYPE_NONE>;
                 interrupt-controller;
                 #interrupt-cells = <2>;
         };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Quoted 6 lines

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Thanks for the information. The "snps,dw-apb-gpio-port" is never used, so I just sent out a series to remove it.

Quoted 6 lines

Quoted 4 lines

I'd actually prefer that you fix the kernel code to actually use it. So that fw_devlink can be backward compatible (Older DT + new kernel). The change is pretty trivial (I just have time to do it for you).

I agree the change is trivial, but it will add some useless LoCs like below.

It's not useless if it preserves backward compatibility with DT.

Quoted 56 lines

I'm not sure whether this is acceptable.So add GPIO and DT maintainers to comment.

Hi Linus, Rob,

Could you please comment? A simple introduction of the problem:

As pointed out by Saravana, "gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it", so once we set fw_devlink=on, then any users of gpio-dwapb as below won't be probed.

device_foo {
          status = "okay"
          ...;
          reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

The compatible string "snps,dw-apb-gpio-port" is never used, but it's in the dt-binding since the dw gpio mainlined. I believe the every dw apb users just copy the compatible string in to soc dtsi. So I submit a series to remove the unused "snps,dw-apb-gpio-port"
But this will break Older DT + new kernel with fw_devlink on. Which solution is better?

If the following patch is acceptable, I can submit it once 5.10-rc1 is out.

thanks

drivers/gpio/gpio-dwapb.c +5 -0

index 1d8d55bd63aa..b8e012e48b59 100644
@@ -19,6 +19,7 @@
  #include <linux/of_address.h>
  #include <linux/of_device.h>
  #include <linux/of_irq.h>
+#include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/property.h>
  #include <linux/reset.h>

@@ -694,6 +695,10 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
         }
         platform_set_drvdata(pdev, gpio);
 
+       err = devm_of_platform_populate(dev);
+       if (err)
+               goto out_unregister;
+
         return 0;
 
  out_unregister:

@@ -820,6 +825,25 @@ static struct platform_driver dwapb_gpio_driver = {
 
  module_platform_driver(dwapb_gpio_driver);
 

Quoted 16 lines

drivers/gpio/gpio-dwapb.c static struct platform_driver dwapb_gpio_driver = { · line 835

Quoted 8 lines

drivers/gpio/gpio-dwapb.c +8 -0

+static const struct of_device_id dwapb_port_of_match[] = {
+       { .compatible = "snps,dw-apb-gpio-port" },
+       { /* Sentinel */ }
+};
+
+static int dwapb_gpio_port_probe(struct platform_device *pdev)
+{
+       return 0;  

No, I'm not asking to do a stub/dummy probe. Move the stuff you do inside device_for_each_child_node{} and dwapb_gpio_add_port() into this probe function. Those two pieces of code together are effectively "probing" a separate gpio controller for each of the child nodes. So just create a real struct device (like we do for every other "compatible" DT node) and probe each of them properly using the device driver core.

Quoted 5 lines

Then I believe the modifications are non-trivial. Maybe Linus and Rob can comment which way is better, fix the dts or modify the gpio-dwapb.c. Personally, I prefer fixing dts, because this doesn't remove or modify any used properties or compatible string, it just removes the unused compatible string.

You appear to be assuming that:

A) There a no consumers of DTBs and DT bindings other than Linux.
B) No Linux user ever updates their kernel image without also updating their DTB.

I can assure you that, in general, neither of those hold true. Hacking

DTs to work around internal implementation details in Linux is rarely if ever a good or even viable idea.

Quoted 178 lines · On Thu, 15 Oct 2020 15:08:33 +0100 Robin Murphy <[email protected]> wrote:

Quoted 169 lines · Jisheng Zhang

Quoted 149 lines · On Thu, 15 Oct 2020 01:48:13 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 82 lines · Jisheng Zhang

Quoted 79 lines · On Wed, 14 Oct 2020 22:04:24 -0700 Saravana Kannan wrote:

Quoted 74 lines · Jisheng Zhang

Quoted 61 lines · On Wed, 14 Oct 2020 10:29:36 -0700 Saravana Kannan <[email protected]> wrote:

Quoted 45 lines · Jisheng Zhang

Hi,

If set fw_devlink as on, any consumers of dw apb gpio won't probe.

The related dts looks like:

gpio0: gpio@2400 {
        compatible = "snps,dw-apb-gpio";
        #address-cells = <1>;
        #size-cells = <0>;

        porta: gpio-port@0 {
               compatible = "snps,dw-apb-gpio-port";
               gpio-controller;
               #gpio-cells = <2>;
               ngpios = <32>;
               reg = <0>;
        };
};

device_foo {
         status = "okay"
         ...;
         reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

If I change the reset-gpio property to use another kind of gpio phandle, e.g gpio expander, then device_foo can be probed successfully.

The gpio expander dt node looks like:

         expander3: gpio@44 {
                 compatible = "fcs,fxl6408";
                 pinctrl-names = "default";
                 pinctrl-0 = <&expander3_pmux>;
                 reg = <0x44>;
                 gpio-controller;
                 #gpio-cells = <2>;
                 interrupt-parent = <&portb>;
                 interrupts = <23 IRQ_TYPE_NONE>;
                 interrupt-controller;
                 #interrupt-cells = <2>;
         };

Quoted 2 lines

The common pattern looks like the devlink can't cope with suppliers from child dt node.

fw_devlink doesn't have any problem dealing with child devices being suppliers. The problem with your case is that the drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it. So change your driver to add the child devices as devices instead of just parsing the node directly and doing stuff with it.

Quoted 6 lines

Either that, or stop putting "compatible" string in a node if you don't plan to actually treat it as a device -- but that's too late for this driver (it needs to be backward compatible). So change the driver to add of_platform_populate() and write a driver that probes "snps,dw-apb-gpio-port".

Thanks for the information. The "snps,dw-apb-gpio-port" is never used, so I just sent out a series to remove it.

Quoted 6 lines

Quoted 4 lines

I'd actually prefer that you fix the kernel code to actually use it. So that fw_devlink can be backward compatible (Older DT + new kernel). The change is pretty trivial (I just have time to do it for you).

I agree the change is trivial, but it will add some useless LoCs like below.

It's not useless if it preserves backward compatibility with DT.

Quoted 56 lines

I'm not sure whether this is acceptable.So add GPIO and DT maintainers to comment.

Hi Linus, Rob,

Could you please comment? A simple introduction of the problem:

As pointed out by Saravana, "gpio-dwapb.c driver directly parses the child nodes and never creates struct devices for them. If you have a node with compatible string, fw_devlink expects you to create and probe a struct device for it", so once we set fw_devlink=on, then any users of gpio-dwapb as below won't be probed.

device_foo {
          status = "okay"
          ...;
          reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
};

The compatible string "snps,dw-apb-gpio-port" is never used, but it's in the dt-binding since the dw gpio mainlined. I believe the every dw apb users just copy the compatible string in to soc dtsi. So I submit a series to remove the unused "snps,dw-apb-gpio-port"
But this will break Older DT + new kernel with fw_devlink on. Which solution is better?

If the following patch is acceptable, I can submit it once 5.10-rc1 is out.

thanks

drivers/gpio/gpio-dwapb.c +5 -0

index 1d8d55bd63aa..b8e012e48b59 100644
@@ -19,6 +19,7 @@
  #include <linux/of_address.h>
  #include <linux/of_device.h>
  #include <linux/of_irq.h>
+#include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/property.h>
  #include <linux/reset.h>

@@ -694,6 +695,10 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
         }
         platform_set_drvdata(pdev, gpio);
 
+       err = devm_of_platform_populate(dev);
+       if (err)
+               goto out_unregister;
+
         return 0;
 
  out_unregister:

@@ -820,6 +825,25 @@ static struct platform_driver dwapb_gpio_driver = {
 
  module_platform_driver(dwapb_gpio_driver);
 

Quoted 16 lines

drivers/gpio/gpio-dwapb.c static struct platform_driver dwapb_gpio_driver = { · line 835

Quoted 8 lines

drivers/gpio/gpio-dwapb.c +8 -0

+static const struct of_device_id dwapb_port_of_match[] = {
+       { .compatible = "snps,dw-apb-gpio-port" },
+       { /* Sentinel */ }
+};
+
+static int dwapb_gpio_port_probe(struct platform_device *pdev)
+{
+       return 0;

No, I'm not asking to do a stub/dummy probe. Move the stuff you do inside device_for_each_child_node{} and dwapb_gpio_add_port() into this probe function. Those two pieces of code together are effectively "probing" a separate gpio controller for each of the child nodes. So just create a real struct device (like we do for every other "compatible" DT node) and probe each of them properly using the device driver core.

Quoted 5 lines

Then I believe the modifications are non-trivial. Maybe Linus and Rob can comment which way is better, fix the dts or modify the gpio-dwapb.c. Personally, I prefer fixing dts, because this doesn't remove or modify any used properties or compatible string, it just removes the unused compatible string.

Quoted 7 lines

You appear to be assuming that:

A) There a no consumers of DTBs and DT bindings other than Linux.
B) No Linux user ever updates their kernel image without also updating their DTB.

I can assure you that, in general, neither of those hold true. Hacking

Just my humble opinion, this is fixing rather than hacking DTs.

Quoted 3 lines

DTs to work around internal implementation details in Linux is rarely if ever a good or even viable idea.

I got your opinion. So it looks like modify the dwapb gpio driver is avoidable. I will submit patch to do so once 5.10-rc1 is out.

But the device link also introduces below warning for all dw-apb-gpio users:

[    0.016113] OF: /soc/apb@f7e80000/gpio@0800/gpio-port@1: could not find phandle
[    0.016197] OF: /soc/apb@f7e80000/gpio@0c00/gpio-port@1: could not find phandle
[    0.016464] OF: /soc/apb@f7e80000/gpio@2400/gpio-port@0: could not find phandle
[    0.016697] OF: /soc/apb@f7fc0000/gpio@8000/gpio-port@4: could not find phandle
[    0.017054] OF: /soc/apb@f7e80000/gpio@0800/gpio-port@1: could not find phandle
[    0.017128] OF: /soc/apb@f7e80000/gpio@0c00/gpio-port@1: could not find phandle