diff mbox series

[stable] gpiolib: Read "gpio-line-names" from a firmware node

Message ID 20210410090919.3157-1-brgl@bgdev.pl
State New
Headers show
Series [stable] gpiolib: Read "gpio-line-names" from a firmware node | expand

Commit Message

Bartosz Golaszewski April 10, 2021, 9:09 a.m. UTC
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

On STM32MP1, the GPIO banks are subnodes of pin-controller@50002000,
see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
pin-controller@50002000 is in drivers/pinctrl/stm32/pinctrl-stm32.c
and iterates over all of its DT subnodes when registering each GPIO
bank gpiochip. Each gpiochip has:

  - gpio_chip.parent = dev,
    where dev is the device node of the pin controller
  - gpio_chip.of_node = np,
    which is the OF node of the GPIO bank

Therefore, dev_fwnode(chip->parent) != of_fwnode_handle(chip.of_node),
i.e. pin-controller@50002000 != pin-controller@50002000/gpio@5000*000.

The original code behaved correctly, as it extracted the "gpio-line-names"
from of_fwnode_handle(chip.of_node) = pin-controller@50002000/gpio@5000*000.

To achieve the same behaviour, read property from the firmware node.

Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
Cc: stable@vger.kernel.org
Reported-by: Marek Vasut <marex@denx.de>
Reported-by: Roman Guskov <rguskov@dh-electronics.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Marek Vasut <marex@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
Hi Greg,

This patch somehow got lost and never made its way into stable. Could you
please apply it?

Thanks,
Bartosz

 drivers/gpio/gpiolib.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

Comments

Greg KH April 10, 2021, 9:15 a.m. UTC | #1
On Sat, Apr 10, 2021 at 11:09:19AM +0200, Bartosz Golaszewski wrote:
> From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> On STM32MP1, the GPIO banks are subnodes of pin-controller@50002000,
> see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
> pin-controller@50002000 is in drivers/pinctrl/stm32/pinctrl-stm32.c
> and iterates over all of its DT subnodes when registering each GPIO
> bank gpiochip. Each gpiochip has:
> 
>   - gpio_chip.parent = dev,
>     where dev is the device node of the pin controller
>   - gpio_chip.of_node = np,
>     which is the OF node of the GPIO bank
> 
> Therefore, dev_fwnode(chip->parent) != of_fwnode_handle(chip.of_node),
> i.e. pin-controller@50002000 != pin-controller@50002000/gpio@5000*000.
> 
> The original code behaved correctly, as it extracted the "gpio-line-names"
> from of_fwnode_handle(chip.of_node) = pin-controller@50002000/gpio@5000*000.
> 
> To achieve the same behaviour, read property from the firmware node.
> 
> Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
> Cc: stable@vger.kernel.org
> Reported-by: Marek Vasut <marex@denx.de>
> Reported-by: Roman Guskov <rguskov@dh-electronics.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Tested-by: Marek Vasut <marex@denx.de>
> Reviewed-by: Marek Vasut <marex@denx.de>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> Hi Greg,
> 
> This patch somehow got lost and never made its way into stable. Could you
> please apply it?

What is the git commit id of it in Linus's tree?

thanks,

greg k-h
Fabio Estevam April 10, 2021, 12:01 p.m. UTC | #2
Hi Greg,

On Sat, Apr 10, 2021 at 6:15 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:

> What is the git commit id of it in Linus's tree?

It is b41ba2ec54a70908067034f139aa23d0dd2985ce

Thanks
Greg KH April 10, 2021, 12:07 p.m. UTC | #3
On Sat, Apr 10, 2021 at 11:09:19AM +0200, Bartosz Golaszewski wrote:
> From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> On STM32MP1, the GPIO banks are subnodes of pin-controller@50002000,
> see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
> pin-controller@50002000 is in drivers/pinctrl/stm32/pinctrl-stm32.c
> and iterates over all of its DT subnodes when registering each GPIO
> bank gpiochip. Each gpiochip has:
> 
>   - gpio_chip.parent = dev,
>     where dev is the device node of the pin controller
>   - gpio_chip.of_node = np,
>     which is the OF node of the GPIO bank
> 
> Therefore, dev_fwnode(chip->parent) != of_fwnode_handle(chip.of_node),
> i.e. pin-controller@50002000 != pin-controller@50002000/gpio@5000*000.
> 
> The original code behaved correctly, as it extracted the "gpio-line-names"
> from of_fwnode_handle(chip.of_node) = pin-controller@50002000/gpio@5000*000.
> 
> To achieve the same behaviour, read property from the firmware node.
> 
> Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
> Cc: stable@vger.kernel.org
> Reported-by: Marek Vasut <marex@denx.de>
> Reported-by: Roman Guskov <rguskov@dh-electronics.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Tested-by: Marek Vasut <marex@denx.de>
> Reviewed-by: Marek Vasut <marex@denx.de>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> Hi Greg,
> 
> This patch somehow got lost and never made its way into stable. Could you
> please apply it?

This has been added and removed more times than I can remember already.

Are you all _SURE_ this is safe for a stable kernel release?  Look in
the archives for complaints when we added this in the past.

thanks,

greg k-h
Marek Vasut April 10, 2021, 1:20 p.m. UTC | #4
On 4/10/21 2:07 PM, Greg Kroah-Hartman wrote:
> On Sat, Apr 10, 2021 at 11:09:19AM +0200, Bartosz Golaszewski wrote:
>> From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>>
>> On STM32MP1, the GPIO banks are subnodes of pin-controller@50002000,
>> see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
>> pin-controller@50002000 is in drivers/pinctrl/stm32/pinctrl-stm32.c
>> and iterates over all of its DT subnodes when registering each GPIO
>> bank gpiochip. Each gpiochip has:
>>
>>    - gpio_chip.parent = dev,
>>      where dev is the device node of the pin controller
>>    - gpio_chip.of_node = np,
>>      which is the OF node of the GPIO bank
>>
>> Therefore, dev_fwnode(chip->parent) != of_fwnode_handle(chip.of_node),
>> i.e. pin-controller@50002000 != pin-controller@50002000/gpio@5000*000.
>>
>> The original code behaved correctly, as it extracted the "gpio-line-names"
>> from of_fwnode_handle(chip.of_node) = pin-controller@50002000/gpio@5000*000.
>>
>> To achieve the same behaviour, read property from the firmware node.
>>
>> Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
>> Cc: stable@vger.kernel.org
>> Reported-by: Marek Vasut <marex@denx.de>
>> Reported-by: Roman Guskov <rguskov@dh-electronics.com>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>> Tested-by: Marek Vasut <marex@denx.de>
>> Reviewed-by: Marek Vasut <marex@denx.de>
>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>> ---
>> Hi Greg,
>>
>> This patch somehow got lost and never made its way into stable. Could you
>> please apply it?
> 
> This has been added and removed more times than I can remember already.
> 
> Are you all _SURE_ this is safe for a stable kernel release?  Look in
> the archives for complaints when we added this in the past.

I now tested this on stm32mp1, which was the original platform that got 
affected by the problem this is supposed to fix, and I can confirm this 
patch fixes the problem there.

So for what it's worth
Tested-by: Marek Vasut <marex@denx.de> # on stm32mp1
Bartosz Golaszewski April 10, 2021, 1:23 p.m. UTC | #5
On Sat, Apr 10, 2021 at 2:07 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Sat, Apr 10, 2021 at 11:09:19AM +0200, Bartosz Golaszewski wrote:
> > From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> >
> > On STM32MP1, the GPIO banks are subnodes of pin-controller@50002000,
> > see arch/arm/boot/dts/stm32mp151.dtsi. The driver for
> > pin-controller@50002000 is in drivers/pinctrl/stm32/pinctrl-stm32.c
> > and iterates over all of its DT subnodes when registering each GPIO
> > bank gpiochip. Each gpiochip has:
> >
> >   - gpio_chip.parent = dev,
> >     where dev is the device node of the pin controller
> >   - gpio_chip.of_node = np,
> >     which is the OF node of the GPIO bank
> >
> > Therefore, dev_fwnode(chip->parent) != of_fwnode_handle(chip.of_node),
> > i.e. pin-controller@50002000 != pin-controller@50002000/gpio@5000*000.
> >
> > The original code behaved correctly, as it extracted the "gpio-line-names"
> > from of_fwnode_handle(chip.of_node) = pin-controller@50002000/gpio@5000*000.
> >
> > To achieve the same behaviour, read property from the firmware node.
> >
> > Fixes: 7cba1a4d5e162 ("gpiolib: generalize devprop_gpiochip_set_names() for device properties")
> > Cc: stable@vger.kernel.org
> > Reported-by: Marek Vasut <marex@denx.de>
> > Reported-by: Roman Guskov <rguskov@dh-electronics.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Tested-by: Marek Vasut <marex@denx.de>
> > Reviewed-by: Marek Vasut <marex@denx.de>
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > ---
> > Hi Greg,
> >
> > This patch somehow got lost and never made its way into stable. Could you
> > please apply it?
>
> This has been added and removed more times than I can remember already.
>
> Are you all _SURE_ this is safe for a stable kernel release?  Look in
> the archives for complaints when we added this in the past.
>
> thanks,
>
> greg k-h

IIRC it fixed the stm32mp1 problem but exposed a different problem
breaking other users until Andy fixed the deeper issue elsewhere.

It's now fine to apply it.

Bartosz
diff mbox series

Patch

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 4253837f870b..7ec0822c0505 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -367,22 +367,18 @@  static int gpiochip_set_desc_names(struct gpio_chip *gc)
  *
  * Looks for device property "gpio-line-names" and if it exists assigns
  * GPIO line names for the chip. The memory allocated for the assigned
- * names belong to the underlying software node and should not be released
+ * names belong to the underlying firmware node and should not be released
  * by the caller.
  */
 static int devprop_gpiochip_set_names(struct gpio_chip *chip)
 {
 	struct gpio_device *gdev = chip->gpiodev;
-	struct device *dev = chip->parent;
+	struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
 	const char **names;
 	int ret, i;
 	int count;
 
-	/* GPIO chip may not have a parent device whose properties we inspect. */
-	if (!dev)
-		return 0;
-
-	count = device_property_string_array_count(dev, "gpio-line-names");
+	count = fwnode_property_string_array_count(fwnode, "gpio-line-names");
 	if (count < 0)
 		return 0;
 
@@ -396,7 +392,7 @@  static int devprop_gpiochip_set_names(struct gpio_chip *chip)
 	if (!names)
 		return -ENOMEM;
 
-	ret = device_property_read_string_array(dev, "gpio-line-names",
+	ret = fwnode_property_read_string_array(fwnode, "gpio-line-names",
 						names, count);
 	if (ret < 0) {
 		dev_warn(&gdev->dev, "failed to read GPIO line names\n");