[PATCH] gpio: max77620: Make the irqchip immutable

[PATCH] gpio: max77620: Make the irqchip immutable

[Jon Hunter]

Commit 6c846d026d49 ("gpio: Don't fiddle with irqchips marked as
immutable") added a warning to indicate if the gpiolib is altering the
internals of irqchips. Following this change the following warning is
now observed for the max77620 gpio driver ...

 WARNING KERN gpio gpiochip0: (max77620-gpio): not an immutable chip,
 	please consider fixing it!

Fix the above warning by making the max77620 gpio driver immutable.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
---
This warning is observed with v5.18-rc5 and so it would be great if
we can fix for v5.18. This is triggering a kernel warning test failure
on one of our platforms.

 drivers/gpio/gpio-max77620.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-max77620.c b/drivers/gpio/gpio-max77620.c
index ebf9dea6546b..aa92658780d6 100644
--- a/drivers/gpio/gpio-max77620.c
+++ b/drivers/gpio/gpio-max77620.c
@@ -119,14 +119,23 @@ static void max77620_gpio_bus_sync_unlock(struct irq_data *data)
 	mutex_unlock(&gpio->buslock);
 }
 
-static struct irq_chip max77620_gpio_irqchip = {
+static void max77620_gpio_irq_print_chip(struct irq_data *data, struct seq_file *p)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+
+	seq_printf(p, dev_name(gc->parent));
+}
+
+static const struct irq_chip max77620_gpio_irqchip = {
 	.name		= "max77620-gpio",
 	.irq_mask	= max77620_gpio_irq_mask,
 	.irq_unmask	= max77620_gpio_irq_unmask,
 	.irq_set_type	= max77620_gpio_set_irq_type,
 	.irq_bus_lock	= max77620_gpio_bus_lock,
 	.irq_bus_sync_unlock = max77620_gpio_bus_sync_unlock,
-	.flags		= IRQCHIP_MASK_ON_SUSPEND,
+	.irq_print_chip	= max77620_gpio_irq_print_chip,
+	.flags		= IRQCHIP_IMMUTABLE | IRQCHIP_MASK_ON_SUSPEND,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };
 
 static int max77620_gpio_dir_input(struct gpio_chip *gc, unsigned int offset)
@@ -318,7 +327,7 @@ static int max77620_gpio_probe(struct platform_device *pdev)
 	mgpio->gpio_chip.base = -1;
 
 	girq = &mgpio->gpio_chip.irq;
-	girq->chip = &max77620_gpio_irqchip;
+	gpio_irq_chip_set_chip(girq, &max77620_gpio_irqchip);
 	/* This will let us handle the parent IRQ in the driver */
 	girq->parent_handler = NULL;
 	girq->num_parents = 0;
-- 
2.25.1

Re: [PATCH] gpio: max77620: Make the irqchip immutable

[Marc Zyngier]

Hi Jon,

On Wed, 04 May 2022 12:19:36 +0100,
Jon Hunter <jonathanh@nvidia.com> wrote:
> 
> Commit 6c846d026d49 ("gpio: Don't fiddle with irqchips marked as
> immutable") added a warning to indicate if the gpiolib is altering the
> internals of irqchips. Following this change the following warning is
> now observed for the max77620 gpio driver ...
> 
>  WARNING KERN gpio gpiochip0: (max77620-gpio): not an immutable chip,
>  	please consider fixing it!
> 
> Fix the above warning by making the max77620 gpio driver immutable.

Thanks for looking into this. Comments below.

> 
> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
> ---
> This warning is observed with v5.18-rc5 and so it would be great if
> we can fix for v5.18. This is triggering a kernel warning test failure
> on one of our platforms.

I'm surprised. This is definitely *not* 5.18 material, and I can't see
the patches in Linus' tree. Are you sure you're not running -next
instead?

> 
>  drivers/gpio/gpio-max77620.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-max77620.c b/drivers/gpio/gpio-max77620.c
> index ebf9dea6546b..aa92658780d6 100644
> --- a/drivers/gpio/gpio-max77620.c
> +++ b/drivers/gpio/gpio-max77620.c
> @@ -119,14 +119,23 @@ static void max77620_gpio_bus_sync_unlock(struct irq_data *data)
>  	mutex_unlock(&gpio->buslock);
>  }
>  
> -static struct irq_chip max77620_gpio_irqchip = {
> +static void max77620_gpio_irq_print_chip(struct irq_data *data, struct seq_file *p)
> +{
> +	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
> +
> +	seq_printf(p, dev_name(gc->parent));
> +}
> +

I'd rather you don't do this. This was added as a band-aid for drivers
that display a device-specific string in /proc/interrupts, and that we
cannot fix because the string is in effect an ABI.

Here, you're going in the opposite direction (making the name
device-specific while it was constant so far). This has the same
ABI-breaking effect, and we shouldn't do that. It is also rather
pointless, as we already have all the required debugging information
in debugfs (and I assume that this is the reason this is added).

> +static const struct irq_chip max77620_gpio_irqchip = {
>  	.name		= "max77620-gpio",
>  	.irq_mask	= max77620_gpio_irq_mask,
>  	.irq_unmask	= max77620_gpio_irq_unmask,

You seem to be missing the updates for these two functions. Please see
the updated documentation in commit 5644b66a9c63 ("Documentation:
Update the recommended pattern for GPIO irqchips").

>  	.irq_set_type	= max77620_gpio_set_irq_type,
>  	.irq_bus_lock	= max77620_gpio_bus_lock,
>  	.irq_bus_sync_unlock = max77620_gpio_bus_sync_unlock,
> -	.flags		= IRQCHIP_MASK_ON_SUSPEND,
> +	.irq_print_chip	= max77620_gpio_irq_print_chip,
> +	.flags		= IRQCHIP_IMMUTABLE | IRQCHIP_MASK_ON_SUSPEND,
> +	GPIOCHIP_IRQ_RESOURCE_HELPERS,
>  };
>  
>  static int max77620_gpio_dir_input(struct gpio_chip *gc, unsigned int offset)
> @@ -318,7 +327,7 @@ static int max77620_gpio_probe(struct platform_device *pdev)
>  	mgpio->gpio_chip.base = -1;
>  
>  	girq = &mgpio->gpio_chip.irq;
> -	girq->chip = &max77620_gpio_irqchip;
> +	gpio_irq_chip_set_chip(girq, &max77620_gpio_irqchip);
>  	/* This will let us handle the parent IRQ in the driver */
>  	girq->parent_handler = NULL;
>  	girq->num_parents = 0;
> -- 
> 2.25.1
> 
> 

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH] gpio: max77620: Make the irqchip immutable

[Jon Hunter]

On 04/05/2022 12:35, Marc Zyngier wrote:
> Hi Jon,
> 
> On Wed, 04 May 2022 12:19:36 +0100,
> Jon Hunter <jonathanh@nvidia.com> wrote:
>>
>> Commit 6c846d026d49 ("gpio: Don't fiddle with irqchips marked as
>> immutable") added a warning to indicate if the gpiolib is altering the
>> internals of irqchips. Following this change the following warning is
>> now observed for the max77620 gpio driver ...
>>
>>   WARNING KERN gpio gpiochip0: (max77620-gpio): not an immutable chip,
>>   	please consider fixing it!
>>
>> Fix the above warning by making the max77620 gpio driver immutable.
> 
> Thanks for looking into this. Comments below.
> 
>>
>> Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
>> ---
>> This warning is observed with v5.18-rc5 and so it would be great if
>> we can fix for v5.18. This is triggering a kernel warning test failure
>> on one of our platforms.
> 
> I'm surprised. This is definitely *not* 5.18 material, and I can't see
> the patches in Linus' tree. Are you sure you're not running -next
> instead?

Ah, you are correct, it was -next and not v5.18-rc5!

>>
>>   drivers/gpio/gpio-max77620.c | 15 ++++++++++++---
>>   1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpio/gpio-max77620.c b/drivers/gpio/gpio-max77620.c
>> index ebf9dea6546b..aa92658780d6 100644
>> --- a/drivers/gpio/gpio-max77620.c
>> +++ b/drivers/gpio/gpio-max77620.c
>> @@ -119,14 +119,23 @@ static void max77620_gpio_bus_sync_unlock(struct irq_data *data)
>>   	mutex_unlock(&gpio->buslock);
>>   }
>>   
>> -static struct irq_chip max77620_gpio_irqchip = {
>> +static void max77620_gpio_irq_print_chip(struct irq_data *data, struct seq_file *p)
>> +{
>> +	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
>> +
>> +	seq_printf(p, dev_name(gc->parent));
>> +}
>> +
> 
> I'd rather you don't do this. This was added as a band-aid for drivers
> that display a device-specific string in /proc/interrupts, and that we
> cannot fix because the string is in effect an ABI.
> 
> Here, you're going in the opposite direction (making the name
> device-specific while it was constant so far). This has the same
> ABI-breaking effect, and we shouldn't do that. It is also rather
> pointless, as we already have all the required debugging information
> in debugfs (and I assume that this is the reason this is added).


OK, I will drop this.

>> +static const struct irq_chip max77620_gpio_irqchip = {
>>   	.name		= "max77620-gpio",
>>   	.irq_mask	= max77620_gpio_irq_mask,
>>   	.irq_unmask	= max77620_gpio_irq_unmask,
> 
> You seem to be missing the updates for these two functions. Please see
> the updated documentation in commit 5644b66a9c63 ("Documentation:
> Update the recommended pattern for GPIO irqchips").

Yes I see. OK, I will add that.

Thanks! Jon

-- 
nvpublic