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

PATCH In review Bartosz Golaszewski 4 participants 6 messages Apr 10, 2021

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Bartosz Golaszewski

author

2021-04-10 09:09 UTC #0 lore raw

PATCH 1/1 gpiolib: Read "gpio-line-names" from a firmware node

From: Andy Shevchenko <[email protected]>

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 [email protected]

Reported-by Marek Vasut <[email protected]>

Reported-by Roman Guskov <[email protected]>

Signed-off-by Andy Shevchenko <[email protected]>

Tested-by Marek Vasut <[email protected]>

Reviewed-by Marek Vasut <[email protected]>

Signed-off-by Bartosz Golaszewski <[email protected]>

---
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(-)

drivers/gpio/gpiolib.c +4 -8

index 4253837f870b..7ec0822c0505 100644
@@ -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");

Signature · 1 line

2.30.1

Greg Kroah-Hartman

maintainer

2021-04-10 09:15 UTC #1 lore raw

Quoted 29 lines · Bartosz Golaszewski

From: Andy Shevchenko <[email protected]>
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 [email protected]
Reported-by Marek Vasut <[email protected]>
Reported-by Roman Guskov <[email protected]>
Signed-off-by Andy Shevchenko <[email protected]>
Tested-by Marek Vasut <[email protected]>
Reviewed-by Marek Vasut <[email protected]>
Signed-off-by Bartosz Golaszewski <[email protected]>

Quoted 5 lines

---
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

2021-04-10 12:01 UTC #2 lore raw

Hi Greg,

Quoted 1 line · Greg Kroah-Hartman

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

It is b41ba2ec54a70908067034f139aa23d0dd2985ce

Thanks

Greg Kroah-Hartman

maintainer

2021-04-10 12:07 UTC #3 lore raw

In reply to Bartosz Golaszewski

Quoted 29 lines · Bartosz Golaszewski

From: Andy Shevchenko <[email protected]>
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 [email protected]
Reported-by Marek Vasut <[email protected]>
Reported-by Roman Guskov <[email protected]>
Signed-off-by Andy Shevchenko <[email protected]>
Tested-by Marek Vasut <[email protected]>
Reviewed-by Marek Vasut <[email protected]>
Signed-off-by Bartosz Golaszewski <[email protected]>

Quoted 5 lines

---
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

Tested-by

2021-04-10 13:21 UTC #4 lore raw

Quoted 33 lines · Greg Kroah-Hartman

Quoted 32 lines · Bartosz Golaszewski
From: Andy Shevchenko <[email protected]>
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 [email protected]
Reported-by Marek Vasut <[email protected]>
Reported-by Roman Guskov <[email protected]>
Signed-off-by Andy Shevchenko <[email protected]>
Tested-by Marek Vasut <[email protected]>
Reviewed-by Marek Vasut <[email protected]>
Signed-off-by Bartosz Golaszewski <[email protected]>
---
Hi Greg,

Quoted 7 lines

Quoted 2 lines
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 <[email protected]> # on stm32mp1

Bartosz Golaszewski

author

2021-04-10 13:23 UTC #5 lore raw

In reply to Greg Kroah-Hartman

Quoted 37 lines · Greg Kroah-Hartman

Quoted 29 lines · Bartosz Golaszewski
From: Andy Shevchenko <[email protected]>
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 [email protected]
Reported-by Marek Vasut <[email protected]>
Reported-by Roman Guskov <[email protected]>
Signed-off-by Andy Shevchenko <[email protected]>
Tested-by Marek Vasut <[email protected]>
Reviewed-by Marek Vasut <[email protected]>
Signed-off-by Bartosz Golaszewski <[email protected]>
Quoted 5 lines
---
Hi Greg,
This patch somehow got lost and never made its way into stable. Could you please apply it?

Quoted 8 lines

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