2023-02-14 07:36:51

by Alexander Stein

[permalink] [raw]
Subject: [PATCH 1/1] gpio: vf610: make irq_chip immutable

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 <[email protected]>
---
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



2023-02-14 10:52:21

by Andy Shevchenko

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

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



2023-02-15 10:18:22

by Linus Walleij

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

On Tue, Feb 14, 2023 at 11:52 AM <[email protected]> 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

2023-02-15 10:19:54

by Linus Walleij

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

On Tue, Feb 14, 2023 at 8:36 AM Alexander Stein
<[email protected]> 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 <[email protected]>

Looks good to me, CC to Marc Z.

Reviewed-by: Linus Walleij <[email protected]>

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

2023-02-15 11:09:41

by Alexander Stein

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

Am Mittwoch, 15. Februar 2023, 11:18:06 CET schrieb Linus Walleij:
> On Tue, Feb 14, 2023 at 11:52 AM <[email protected]> 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


--
TQ-Systems GmbH | M?hlstra?e 2, Gut Delling | 82229 Seefeld, Germany
Amtsgericht M?nchen, HRB 105018
Gesch?ftsf?hrer: Detlef Schneider, R?diger Stahl, Stefan Schneider
http://www.tq-group.com/



2023-02-15 11:16:25

by Marc Zyngier

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

On Wed, 15 Feb 2023 10:19:28 +0000,
Linus Walleij <[email protected]> wrote:
>
> On Tue, Feb 14, 2023 at 8:36 AM Alexander Stein
> <[email protected]> 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 <[email protected]>
>
> 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 <[email protected]>
>
> 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.

2023-02-15 11:19:59

by Linus Walleij

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

On Wed, Feb 15, 2023 at 12:09 PM Alexander Stein
<[email protected]> wrote:
> Am Mittwoch, 15. Februar 2023, 11:18:06 CET schrieb Linus Walleij:
> > On Tue, Feb 14, 2023 at 11:52 AM <[email protected]> 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

2023-02-15 11:33:55

by Linus Walleij

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

On Wed, Feb 15, 2023 at 12:16 PM Marc Zyngier <[email protected]> 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

2023-02-15 11:51:46

by Andy Shevchenko

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

On Wed, Feb 15, 2023 at 12:18 PM Linus Walleij <[email protected]> wrote:
> On Tue, Feb 14, 2023 at 11:52 AM <[email protected]> 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