[PATCH] gpio: nomadik: Back out some managed resources

[PATCH] gpio: nomadik: Back out some managed resources

[Linus Walleij]

Several commits introduce managed resources (devm_*) into the
nmk_gpio_populate_chip() function.

This isn't always working because when called from the Nomadik pin
control driver we just want to populate some states for the device as
the same states are used by the pin control driver.

Some managed resources such as devm_kzalloc() etc will work, as the
passed in platform device will be used for lifecycle management,
but in some cases where we used the looked-up platform device
for the GPIO block, this will cause problems for the combined
pin control and GPIO driver, because it adds managed resources
to the GPIO device before it is probed, which is something that
the device core will not accept, and all of the GPIO blocks will
refuse to probe:

platform 8012e000.gpio: Resources present before probing
platform 8012e080.gpio: Resources present before probing
(...)

Fix this by not tying any managed resources to the looked-up
gpio_pdev/gpio_dev device, let's just live with the fact that
these need imperative resource management for now.

Drop in some notes and use a local *dev variable to clarify the
code.

Cc: Théo Lebrun <theo.lebrun@bootlin.com>
Fixes: 12410e95903c ("gpio: nomadik: use devm_platform_ioremap_resource() helper")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpio-nomadik.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/gpio/gpio-nomadik.c b/drivers/gpio/gpio-nomadik.c
index 483086deb397..1ed547491f48 100644
--- a/drivers/gpio/gpio-nomadik.c
+++ b/drivers/gpio/gpio-nomadik.c
@@ -509,9 +509,11 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
 {
 	struct nmk_gpio_chip *nmk_chip;
 	struct platform_device *gpio_pdev;
+	struct device *dev = &pdev->dev;
 	struct reset_control *reset;
 	struct device *gpio_dev;
 	struct gpio_chip *chip;
+	struct resource *res;
 	struct clk *clk;
 	void __iomem *base;
 	u32 id, ngpio;
@@ -519,13 +521,13 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
 
 	gpio_dev = bus_find_device_by_fwnode(&platform_bus_type, fwnode);
 	if (!gpio_dev) {
-		dev_err(&pdev->dev, "populate \"%pfwP\": device not found\n", fwnode);
+		dev_err(dev, "populate \"%pfwP\": device not found\n", fwnode);
 		return ERR_PTR(-ENODEV);
 	}
 	gpio_pdev = to_platform_device(gpio_dev);
 
 	if (device_property_read_u32(gpio_dev, "gpio-bank", &id)) {
-		dev_err(&pdev->dev, "populate: gpio-bank property not found\n");
+		dev_err(dev, "populate: gpio-bank property not found\n");
 		platform_device_put(gpio_pdev);
 		return ERR_PTR(-EINVAL);
 	}
@@ -539,7 +541,7 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
 	}
 #endif
 
-	nmk_chip = devm_kzalloc(&pdev->dev, sizeof(*nmk_chip), GFP_KERNEL);
+	nmk_chip = devm_kzalloc(dev, sizeof(*nmk_chip), GFP_KERNEL);
 	if (!nmk_chip) {
 		platform_device_put(gpio_pdev);
 		return ERR_PTR(-ENOMEM);
@@ -547,7 +549,7 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
 
 	if (device_property_read_u32(gpio_dev, "ngpios", &ngpio)) {
 		ngpio = NMK_GPIO_PER_CHIP;
-		dev_dbg(&pdev->dev, "populate: using default ngpio (%d)\n", ngpio);
+		dev_dbg(dev, "populate: using default ngpio (%d)\n", ngpio);
 	}
 
 	nmk_chip->is_mobileye_soc = device_is_compatible(gpio_dev,
@@ -559,14 +561,17 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
 	chip->label = dev_name(gpio_dev);
 	chip->parent = gpio_dev;
 
-	base = devm_platform_ioremap_resource(pdev, 0);
+	/* NOTE: different devices! No devm_platform_ioremap_resource() here! */
+	res = platform_get_resource(gpio_pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
 	if (IS_ERR(base)) {
 		platform_device_put(gpio_pdev);
 		return ERR_CAST(base);
 	}
 	nmk_chip->addr = base;
 
-	clk = devm_clk_get_optional(gpio_dev, NULL);
+	/* NOTE: do not use devm_ here! */
+	clk = clk_get_optional(gpio_dev, NULL);
 	if (IS_ERR(clk)) {
 		platform_device_put(gpio_pdev);
 		return (void *)clk;
@@ -574,9 +579,10 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
 	clk_prepare(clk);
 	nmk_chip->clk = clk;
 
-	reset = devm_reset_control_get_optional_shared(gpio_dev, NULL);
+	/* NOTE: do not use devm_ here! */
+	reset = reset_control_get_optional_shared(gpio_dev, NULL);
 	if (IS_ERR(reset)) {
-		dev_err(&pdev->dev, "failed getting reset control: %ld\n",
+		dev_err(dev, "failed getting reset control: %ld\n",
 			PTR_ERR(reset));
 		return ERR_CAST(reset);
 	}
@@ -588,7 +594,7 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
 	 */
 	ret = reset_control_deassert(reset);
 	if (ret) {
-		dev_err(&pdev->dev, "failed reset deassert: %d\n", ret);
+		dev_err(dev, "failed reset deassert: %d\n", ret);
 		return ERR_PTR(ret);
 	}
 

---
base-commit: caddc92c57451d983c7e31e60b961c5aae4ece63
change-id: 20240305-fix-nomadik-gpio-50f2dddaa2dd

Best regards,
-- 
Linus Walleij <linus.walleij@linaro.org>

Re: [PATCH] gpio: nomadik: Back out some managed resources

[Théo Lebrun]

Hello,

On Tue Mar 5, 2024 at 9:26 AM CET, Linus Walleij wrote:
> Several commits introduce managed resources (devm_*) into the
> nmk_gpio_populate_chip() function.
>
> This isn't always working because when called from the Nomadik pin
> control driver we just want to populate some states for the device as
> the same states are used by the pin control driver.
>
> Some managed resources such as devm_kzalloc() etc will work, as the
> passed in platform device will be used for lifecycle management,
> but in some cases where we used the looked-up platform device
> for the GPIO block, this will cause problems for the combined
> pin control and GPIO driver, because it adds managed resources
> to the GPIO device before it is probed, which is something that
> the device core will not accept, and all of the GPIO blocks will
> refuse to probe:
>
> platform 8012e000.gpio: Resources present before probing
> platform 8012e080.gpio: Resources present before probing
> (...)
>
> Fix this by not tying any managed resources to the looked-up
> gpio_pdev/gpio_dev device, let's just live with the fact that
> these need imperative resource management for now.
>
> Drop in some notes and use a local *dev variable to clarify the
> code.
>
> Cc: Théo Lebrun <theo.lebrun@bootlin.com>
> Fixes: 12410e95903c ("gpio: nomadik: use devm_platform_ioremap_resource() helper")
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Thanks Linus for this follow-up. Makes complete sense. Tested on
Mobileye hardware.

This nmk_gpio_populate_chip() function being called by two different
platform drivers makes for a complex setup. I should have been more
wary when modifying it.

Tested-by: Théo Lebrun <theo.lebrun@bootlin.com>

Regards,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH] gpio: nomadik: Back out some managed resources

[Andy Shevchenko]

On Tue, Mar 5, 2024 at 10:26 AM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> Several commits introduce managed resources (devm_*) into the
> nmk_gpio_populate_chip() function.
>
> This isn't always working because when called from the Nomadik pin
> control driver we just want to populate some states for the device as
> the same states are used by the pin control driver.
>
> Some managed resources such as devm_kzalloc() etc will work, as the
> passed in platform device will be used for lifecycle management,
> but in some cases where we used the looked-up platform device
> for the GPIO block, this will cause problems for the combined
> pin control and GPIO driver, because it adds managed resources
> to the GPIO device before it is probed, which is something that
> the device core will not accept, and all of the GPIO blocks will
> refuse to probe:
>
> platform 8012e000.gpio: Resources present before probing
> platform 8012e080.gpio: Resources present before probing
> (...)
>
> Fix this by not tying any managed resources to the looked-up
> gpio_pdev/gpio_dev device, let's just live with the fact that
> these need imperative resource management for now.

...

> -       clk = devm_clk_get_optional(gpio_dev, NULL);
> +       /* NOTE: do not use devm_ here! */
> +       clk = clk_get_optional(gpio_dev, NULL);
>         if (IS_ERR(clk)) {
>                 platform_device_put(gpio_pdev);
>                 return (void *)clk;

> -       reset = devm_reset_control_get_optional_shared(gpio_dev, NULL);
> +       /* NOTE: do not use devm_ here! */
> +       reset = reset_control_get_optional_shared(gpio_dev, NULL);
>         if (IS_ERR(reset)) {
> -               dev_err(&pdev->dev, "failed getting reset control: %ld\n",
> +               dev_err(dev, "failed getting reset control: %ld\n",
>                         PTR_ERR(reset));
>                 return ERR_CAST(reset);
>         }
> @@ -588,7 +594,7 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
>          */
>         ret = reset_control_deassert(reset);
>         if (ret) {
> -               dev_err(&pdev->dev, "failed reset deassert: %d\n", ret);
> +               dev_err(dev, "failed reset deassert: %d\n", ret);
>                 return ERR_PTR(ret);
>         }

Yeah, but you forgot to update the error path as it needs to unroll
the changes, no?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] gpio: nomadik: Back out some managed resources

[Théo Lebrun]

Hello,

On Tue Mar 5, 2024 at 6:05 PM CET, Andy Shevchenko wrote:
> On Tue, Mar 5, 2024 at 10:26 AM Linus Walleij <linus.walleij@linaro.org> wrote:
> >
> > Several commits introduce managed resources (devm_*) into the
> > nmk_gpio_populate_chip() function.
> >
> > This isn't always working because when called from the Nomadik pin
> > control driver we just want to populate some states for the device as
> > the same states are used by the pin control driver.
> >
> > Some managed resources such as devm_kzalloc() etc will work, as the
> > passed in platform device will be used for lifecycle management,
> > but in some cases where we used the looked-up platform device
> > for the GPIO block, this will cause problems for the combined
> > pin control and GPIO driver, because it adds managed resources
> > to the GPIO device before it is probed, which is something that
> > the device core will not accept, and all of the GPIO blocks will
> > refuse to probe:
> >
> > platform 8012e000.gpio: Resources present before probing
> > platform 8012e080.gpio: Resources present before probing
> > (...)
> >
> > Fix this by not tying any managed resources to the looked-up
> > gpio_pdev/gpio_dev device, let's just live with the fact that
> > these need imperative resource management for now.
>
> ...
>
> > -       clk = devm_clk_get_optional(gpio_dev, NULL);
> > +       /* NOTE: do not use devm_ here! */
> > +       clk = clk_get_optional(gpio_dev, NULL);
> >         if (IS_ERR(clk)) {
> >                 platform_device_put(gpio_pdev);
> >                 return (void *)clk;
>
> > -       reset = devm_reset_control_get_optional_shared(gpio_dev, NULL);
> > +       /* NOTE: do not use devm_ here! */
> > +       reset = reset_control_get_optional_shared(gpio_dev, NULL);
> >         if (IS_ERR(reset)) {
> > -               dev_err(&pdev->dev, "failed getting reset control: %ld\n",
> > +               dev_err(dev, "failed getting reset control: %ld\n",
> >                         PTR_ERR(reset));
> >                 return ERR_CAST(reset);
> >         }
> > @@ -588,7 +594,7 @@ struct nmk_gpio_chip *nmk_gpio_populate_chip(struct fwnode_handle *fwnode,
> >          */
> >         ret = reset_control_deassert(reset);
> >         if (ret) {
> > -               dev_err(&pdev->dev, "failed reset deassert: %d\n", ret);
> > +               dev_err(dev, "failed reset deassert: %d\n", ret);
> >                 return ERR_PTR(ret);
> >         }
>
> Yeah, but you forgot to update the error path as it needs to unroll
> the changes, no?

About error cases: platform_device_put() calls are missing from the last
two error cases (reset-related).

Regards,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com