[PATCH 1/1] gpio: vf610: make irq_chip immutable

[PATCH 1/1] gpio: vf610: make irq_chip immutable

[Alexander Stein]

Since recently, the kernel is nagging about mutable irq_chips:

    "not an immutable chip, please consider fixing it!"

Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
helper functions and call the appropriate gpiolib functions.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
---
The overall changes are based on commit f1138dacb7ff
("gpio: sch: make irq_chip immutable")

 drivers/gpio/gpio-vf610.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/gpio/gpio-vf610.c b/drivers/gpio/gpio-vf610.c
index a429176673e7..e63ca8c85bec 100644
--- a/drivers/gpio/gpio-vf610.c
+++ b/drivers/gpio/gpio-vf610.c
@@ -30,7 +30,6 @@ struct fsl_gpio_soc_data {
 
 struct vf610_gpio_port {
 	struct gpio_chip gc;
-	struct irq_chip ic;
 	void __iomem *base;
 	void __iomem *gpio_base;
 	const struct fsl_gpio_soc_data *sdata;
@@ -237,6 +236,17 @@ static int vf610_gpio_irq_set_wake(struct irq_data *d, u32 enable)
 	return 0;
 }
 
+static const struct irq_chip vf610_irqchip = {
+	.name = "gpio-vf610",
+	.irq_ack = vf610_gpio_irq_ack,
+	.irq_mask = vf610_gpio_irq_mask,
+	.irq_unmask = vf610_gpio_irq_unmask,
+	.irq_set_type = vf610_gpio_irq_set_type,
+	.irq_set_wake = vf610_gpio_irq_set_wake,
+	.flags = IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
 static void vf610_gpio_disable_clk(void *data)
 {
 	clk_disable_unprepare(data);
@@ -249,7 +259,6 @@ static int vf610_gpio_probe(struct platform_device *pdev)
 	struct vf610_gpio_port *port;
 	struct gpio_chip *gc;
 	struct gpio_irq_chip *girq;
-	struct irq_chip *ic;
 	int i;
 	int ret;
 
@@ -315,14 +324,6 @@ static int vf610_gpio_probe(struct platform_device *pdev)
 	gc->direction_output = vf610_gpio_direction_output;
 	gc->set = vf610_gpio_set;
 
-	ic = &port->ic;
-	ic->name = "gpio-vf610";
-	ic->irq_ack = vf610_gpio_irq_ack;
-	ic->irq_mask = vf610_gpio_irq_mask;
-	ic->irq_unmask = vf610_gpio_irq_unmask;
-	ic->irq_set_type = vf610_gpio_irq_set_type;
-	ic->irq_set_wake = vf610_gpio_irq_set_wake;
-
 	/* Mask all GPIO interrupts */
 	for (i = 0; i < gc->ngpio; i++)
 		vf610_gpio_writel(0, port->base + PORT_PCR(i));
@@ -331,7 +332,7 @@ static int vf610_gpio_probe(struct platform_device *pdev)
 	vf610_gpio_writel(~0, port->base + PORT_ISFR);
 
 	girq = &gc->irq;
-	girq->chip = ic;
+	gpio_irq_chip_set_chip(girq, &vf610_irqchip);
 	girq->parent_handler = vf610_gpio_irq_handler;
 	girq->num_parents = 1;
 	girq->parents = devm_kcalloc(&pdev->dev, 1,
-- 
2.34.1

Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[andy.shevchenko]

Tue, Feb 14, 2023 at 08:36:38AM +0100, Alexander Stein kirjoitti:
> Since recently, the kernel is nagging about mutable irq_chips:
> 
>     "not an immutable chip, please consider fixing it!"
> 
> Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
> helper functions and call the appropriate gpiolib functions.

...

> The overall changes are based on commit f1138dacb7ff
> ("gpio: sch: make irq_chip immutable")

Nice, but you forgot one crucial detail. You need to mark GPIO resuested
whenever it's locked as IRQ and otherwise when unlocked.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[Linus Walleij]

On Tue, Feb 14, 2023 at 11:52 AM <andy.shevchenko@gmail.com> wrote:
> Tue, Feb 14, 2023 at 08:36:38AM +0100, Alexander Stein kirjoitti:
> > Since recently, the kernel is nagging about mutable irq_chips:
> >
> >     "not an immutable chip, please consider fixing it!"
> >
> > Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
> > helper functions and call the appropriate gpiolib functions.
>
> ...
>
> > The overall changes are based on commit f1138dacb7ff
> > ("gpio: sch: make irq_chip immutable")
>
> Nice, but you forgot one crucial detail. You need to mark GPIO resuested
> whenever it's locked as IRQ and otherwise when unlocked.

+static const struct irq_chip vf610_irqchip = {
(...)
+       GPIOCHIP_IRQ_RESOURCE_HELPERS,

That's what this macro does ;)

Yours,
Linus Walleij

Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[Linus Walleij]

On Tue, Feb 14, 2023 at 8:36 AM Alexander Stein
<alexander.stein@ew.tq-group.com> wrote:

> Since recently, the kernel is nagging about mutable irq_chips:
>
>     "not an immutable chip, please consider fixing it!"
>
> Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
> helper functions and call the appropriate gpiolib functions.
>
> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>

Looks good to me, CC to Marc Z.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

We fixed quite a few of these now, Marc do you have an idea about
how much we have left until we can make immutable the default?

Yours,
Linus Walleij

Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[Alexander Stein]

Am Mittwoch, 15. Februar 2023, 11:18:06 CET schrieb Linus Walleij:
> On Tue, Feb 14, 2023 at 11:52 AM <andy.shevchenko@gmail.com> wrote:
> > Tue, Feb 14, 2023 at 08:36:38AM +0100, Alexander Stein kirjoitti:
> > > Since recently, the kernel is nagging about mutable irq_chips:
> > >     "not an immutable chip, please consider fixing it!"
> > > 
> > > Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
> > > helper functions and call the appropriate gpiolib functions.
> > 
> > ...
> > 
> > > The overall changes are based on commit f1138dacb7ff
> > > ("gpio: sch: make irq_chip immutable")
> > 
> > Nice, but you forgot one crucial detail. You need to mark GPIO resuested
> > whenever it's locked as IRQ and otherwise when unlocked.
> 
> +static const struct irq_chip vf610_irqchip = {
> (...)
> +       GPIOCHIP_IRQ_RESOURCE_HELPERS,
> 
> That's what this macro does ;)

Does this mean the calls to gpiochip_disable_irq/gpiochip_enable_irq in v2/v3 
are not necessary?

Best regards,
Alexander

> Yours,
> Linus Walleij


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Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[Marc Zyngier]

On Wed, 15 Feb 2023 10:19:28 +0000,
Linus Walleij <linus.walleij@linaro.org> wrote:
> 
> On Tue, Feb 14, 2023 at 8:36 AM Alexander Stein
> <alexander.stein@ew.tq-group.com> wrote:
> 
> > Since recently, the kernel is nagging about mutable irq_chips:
> >
> >     "not an immutable chip, please consider fixing it!"
> >
> > Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
> > helper functions and call the appropriate gpiolib functions.
> >
> > Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> 
> Looks good to me, CC to Marc Z.

Looks wrong to me. This is missing the explicit callbacks into gpiolib
so that it knows what gets enabled/disabled on mask/unmask.

>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> 
> We fixed quite a few of these now, Marc do you have an idea about
> how much we have left until we can make immutable the default?

I haven't tracked that, and making it the default would probably mean
getting rid of the code that patches the irqchip structures. I'd say
that once -rc1 is out, we replace the polite nag with something
nastier (WARN_ON() of some sort), and push that into -next.

Leave the warning in place for a couple of releases (until the next
LTS), and then drop the patching code. The not-so-nice part is that
that drivers that haven't been fixed will break silently. The good
side is that these drivers will not have been touched over 2 LTS
releases, and are thus most likely abandonware.

Thanks,

	M.

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

Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[Linus Walleij]

On Wed, Feb 15, 2023 at 12:09 PM Alexander Stein
<alexander.stein@ew.tq-group.com> wrote:
> Am Mittwoch, 15. Februar 2023, 11:18:06 CET schrieb Linus Walleij:
> > On Tue, Feb 14, 2023 at 11:52 AM <andy.shevchenko@gmail.com> wrote:
> > > Tue, Feb 14, 2023 at 08:36:38AM +0100, Alexander Stein kirjoitti:
> > > > Since recently, the kernel is nagging about mutable irq_chips:
> > > >     "not an immutable chip, please consider fixing it!"
> > > >
> > > > Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
> > > > helper functions and call the appropriate gpiolib functions.
> > >
> > > ...
> > >
> > > > The overall changes are based on commit f1138dacb7ff
> > > > ("gpio: sch: make irq_chip immutable")
> > >
> > > Nice, but you forgot one crucial detail. You need to mark GPIO resuested
> > > whenever it's locked as IRQ and otherwise when unlocked.
> >
> > +static const struct irq_chip vf610_irqchip = {
> > (...)
> > +       GPIOCHIP_IRQ_RESOURCE_HELPERS,
> >
> > That's what this macro does ;)
>
> Does this mean the calls to gpiochip_disable_irq/gpiochip_enable_irq in v2/v3
> are not necessary?

No I guess I just misunderstood Andy's comments about "mark GPIO requested".
The callbacks to gpiolib are needed just like pointed out by Marc Z in his
answer, these callbacks are indeed needed.

Yours,
Linus Walleij

Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[Linus Walleij]

On Wed, Feb 15, 2023 at 12:16 PM Marc Zyngier <maz@kernel.org> wrote:

> > We fixed quite a few of these now, Marc do you have an idea about
> > how much we have left until we can make immutable the default?
>
> I haven't tracked that, and making it the default would probably mean
> getting rid of the code that patches the irqchip structures. I'd say
> that once -rc1 is out, we replace the polite nag with something
> nastier (WARN_ON() of some sort), and push that into -next.
>
> Leave the warning in place for a couple of releases (until the next
> LTS), and then drop the patching code. The not-so-nice part is that
> that drivers that haven't been fixed will break silently. The good
> side is that these drivers will not have been touched over 2 LTS
> releases, and are thus most likely abandonware.

Hmmm I will take a round and fix some more that are simple and
obvious, I know some that are definitely used but just sees low attention
from users.

Yours,
Linus Walleij

Re: [PATCH 1/1] gpio: vf610: make irq_chip immutable

[Andy Shevchenko]

On Wed, Feb 15, 2023 at 12:18 PM Linus Walleij <linus.walleij@linaro.org> wrote:
> On Tue, Feb 14, 2023 at 11:52 AM <andy.shevchenko@gmail.com> wrote:
> > Tue, Feb 14, 2023 at 08:36:38AM +0100, Alexander Stein kirjoitti:
> > > Since recently, the kernel is nagging about mutable irq_chips:
> > >
> > >     "not an immutable chip, please consider fixing it!"
> > >
> > > Drop the unneeded copy, flag it as IRQCHIP_IMMUTABLE, add the new
> > > helper functions and call the appropriate gpiolib functions.
> >
> > ...
> >
> > > The overall changes are based on commit f1138dacb7ff
> > > ("gpio: sch: make irq_chip immutable")
> >
> > Nice, but you forgot one crucial detail. You need to mark GPIO resuested
> > whenever it's locked as IRQ and otherwise when unlocked.
>
> +static const struct irq_chip vf610_irqchip = {
> (...)
> +       GPIOCHIP_IRQ_RESOURCE_HELPERS,
>
> That's what this macro does ;)

Maybe I was unclear, but I meant that the above mentioned macro
requires to have the helpers to be called to enable the GPIO line.


-- 
With Best Regards,
Andy Shevchenko