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[PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property

Hector Palacios posted 3 patches 1 year, 11 months ago
There is a newer version of this series
[PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
Posted by Hector Palacios 1 year, 11 months ago 
Some SoCs, such as i.MX93, don't have all 32 pins available
per port. Allow optional generic 'ngpios' property to be
specified from the device tree and default to
VF610_GPIO_PER_PORT (32) if the property does not exist.

Signed-off-by: Hector Palacios <hector.palacios@digi.com>
---
 drivers/gpio/gpio-vf610.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-vf610.c b/drivers/gpio/gpio-vf610.c
index 07e5e6323e86..4abdf75e9a0a 100644
--- a/drivers/gpio/gpio-vf610.c
+++ b/drivers/gpio/gpio-vf610.c
@@ -276,6 +276,7 @@ static int vf610_gpio_probe(struct platform_device *pdev)
 	struct vf610_gpio_port *port;
 	struct gpio_chip *gc;
 	struct gpio_irq_chip *girq;
+	u32 ngpios;
 	int i;
 	int ret;
 	bool dual_base;
@@ -353,7 +354,11 @@ static int vf610_gpio_probe(struct platform_device *pdev)
 	gc = &port->gc;
 	gc->parent = dev;
 	gc->label = dev_name(dev);
-	gc->ngpio = VF610_GPIO_PER_PORT;
+	ret = device_property_read_u32(dev, "ngpios", &ngpios);
+	if (ret || ngpios > VF610_GPIO_PER_PORT)
+		gc->ngpio = VF610_GPIO_PER_PORT;
+	else
+		gc->ngpio = (u16)ngpios;
 	gc->base = -1;
 
 	gc->request = gpiochip_generic_request;
Re: [PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
Posted by Andy Shevchenko 1 year, 11 months ago 
On Wed, Jan 17, 2024 at 10:35 AM Hector Palacios
<hector.palacios@digi.com> wrote:
>
> Some SoCs, such as i.MX93, don't have all 32 pins available
> per port. Allow optional generic 'ngpios' property to be
> specified from the device tree and default to
> VF610_GPIO_PER_PORT (32) if the property does not exist.

...

> +       ret = device_property_read_u32(dev, "ngpios", &ngpios);
> +       if (ret || ngpios > VF610_GPIO_PER_PORT)
> +               gc->ngpio = VF610_GPIO_PER_PORT;
> +       else
> +               gc->ngpio = (u16)ngpios;

This property is being read by the GPIOLIB core. Why do you need to repeat this?

-- 
With Best Regards,
Andy Shevchenko
Re: [PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
Posted by Hector Palacios 1 year, 11 months ago 
Hello Andy,

On 1/17/24 21:51, Andy Shevchenko wrote:
>> Some SoCs, such as i.MX93, don't have all 32 pins available
>> per port. Allow optional generic 'ngpios' property to be
>> specified from the device tree and default to
>> VF610_GPIO_PER_PORT (32) if the property does not exist.
> 
> ...
> 
>> +       ret = device_property_read_u32(dev, "ngpios", &ngpios);
>> +       if (ret || ngpios > VF610_GPIO_PER_PORT)
>> +               gc->ngpio = VF610_GPIO_PER_PORT;
>> +       else
>> +               gc->ngpio = (u16)ngpios;
> 
> This property is being read by the GPIOLIB core. Why do you need to repeat this?

My apologies; I had not seen this.
I'll use gpiochip_get_ngpios() on the next iteration.

Thank you!
-- 
Héctor Palacios
Re: [PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
Posted by Andy Shevchenko 1 year, 11 months ago 
On Thu, Jan 18, 2024 at 10:25 AM Hector Palacios
<hector.palacios@digi.com> wrote:
> On 1/17/24 21:51, Andy Shevchenko wrote:
> >> Some SoCs, such as i.MX93, don't have all 32 pins available
> >> per port. Allow optional generic 'ngpios' property to be
> >> specified from the device tree and default to
> >> VF610_GPIO_PER_PORT (32) if the property does not exist.

...

> >> +       ret = device_property_read_u32(dev, "ngpios", &ngpios);
> >> +       if (ret || ngpios > VF610_GPIO_PER_PORT)
> >> +               gc->ngpio = VF610_GPIO_PER_PORT;
> >> +       else
> >> +               gc->ngpio = (u16)ngpios;
> >
> > This property is being read by the GPIOLIB core. Why do you need to repeat this?
>
> My apologies; I had not seen this.
> I'll use gpiochip_get_ngpios() on the next iteration.

But still why?
https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib.c#L867

It's called for every driver.

Maybe it's needed to be refactored to allow fallbacks? Then can the
GPIO MMIO case also be updated?

-- 
With Best Regards,
Andy Shevchenko
Re: [PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
Posted by Bartosz Golaszewski 1 year, 11 months ago 
On Thu, Jan 18, 2024 at 10:04 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Thu, Jan 18, 2024 at 10:25 AM Hector Palacios
> <hector.palacios@digi.com> wrote:
> > On 1/17/24 21:51, Andy Shevchenko wrote:
> > >> Some SoCs, such as i.MX93, don't have all 32 pins available
> > >> per port. Allow optional generic 'ngpios' property to be
> > >> specified from the device tree and default to
> > >> VF610_GPIO_PER_PORT (32) if the property does not exist.
>
> ...
>
> > >> +       ret = device_property_read_u32(dev, "ngpios", &ngpios);
> > >> +       if (ret || ngpios > VF610_GPIO_PER_PORT)
> > >> +               gc->ngpio = VF610_GPIO_PER_PORT;
> > >> +       else
> > >> +               gc->ngpio = (u16)ngpios;
> > >
> > > This property is being read by the GPIOLIB core. Why do you need to repeat this?
> >
> > My apologies; I had not seen this.
> > I'll use gpiochip_get_ngpios() on the next iteration.
>
> But still why?
> https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib.c#L867
>
> It's called for every driver.
>
> Maybe it's needed to be refactored to allow fallbacks? Then can the
> GPIO MMIO case also be updated?
>

I guess it's because Hector wants to set an upper limit on the number of GPIOs?

Bart

> --
> With Best Regards,
> Andy Shevchenko
Re: [PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
Posted by Hector Palacios 1 year, 11 months ago 
On 1/18/24 13:03, Bartosz Golaszewski wrote:
> 
> On Thu, Jan 18, 2024 at 10:04 AM Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
>>
>> On Thu, Jan 18, 2024 at 10:25 AM Hector Palacios
>> <hector.palacios@digi.com> wrote:
>>> On 1/17/24 21:51, Andy Shevchenko wrote:
>>>>> Some SoCs, such as i.MX93, don't have all 32 pins available
>>>>> per port. Allow optional generic 'ngpios' property to be
>>>>> specified from the device tree and default to
>>>>> VF610_GPIO_PER_PORT (32) if the property does not exist.
>>
>> ...
>>
>>>>> +       ret = device_property_read_u32(dev, "ngpios", &ngpios);
>>>>> +       if (ret || ngpios > VF610_GPIO_PER_PORT)
>>>>> +               gc->ngpio = VF610_GPIO_PER_PORT;
>>>>> +       else
>>>>> +               gc->ngpio = (u16)ngpios;
>>>>
>>>> This property is being read by the GPIOLIB core. Why do you need to repeat this?
>>>
>>> My apologies; I had not seen this.
>>> I'll use gpiochip_get_ngpios() on the next iteration.
>>
>> But still why?
>> https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib.c#L867
>>
>> It's called for every driver.
>>
>> Maybe it's needed to be refactored to allow fallbacks? Then can the
>> GPIO MMIO case also be updated?
>>
> 
> I guess it's because Hector wants to set an upper limit on the number of GPIOs?

I think Andy is suggesting to rework the gpio-vf610 driver to use 
bgpio_chip struct (it doesn't currently), and then I guess the 'ngpio' 
property gets read automatically if you call bgpio_init().
-- 
Héctor Palacios
Re: [PATCH v3 1/3] gpio: vf610: add support to DT 'ngpios' property
Posted by Bartosz Golaszewski 1 year, 11 months ago 
On Thu, Jan 18, 2024 at 1:45 PM Hector Palacios
<hector.palacios@digi.com> wrote:
>
> On 1/18/24 13:03, Bartosz Golaszewski wrote:
> >
> > On Thu, Jan 18, 2024 at 10:04 AM Andy Shevchenko
> > <andy.shevchenko@gmail.com> wrote:
> >>
> >> On Thu, Jan 18, 2024 at 10:25 AM Hector Palacios
> >> <hector.palacios@digi.com> wrote:
> >>> On 1/17/24 21:51, Andy Shevchenko wrote:
> >>>>> Some SoCs, such as i.MX93, don't have all 32 pins available
> >>>>> per port. Allow optional generic 'ngpios' property to be
> >>>>> specified from the device tree and default to
> >>>>> VF610_GPIO_PER_PORT (32) if the property does not exist.
> >>
> >> ...
> >>
> >>>>> +       ret = device_property_read_u32(dev, "ngpios", &ngpios);
> >>>>> +       if (ret || ngpios > VF610_GPIO_PER_PORT)
> >>>>> +               gc->ngpio = VF610_GPIO_PER_PORT;
> >>>>> +       else
> >>>>> +               gc->ngpio = (u16)ngpios;
> >>>>
> >>>> This property is being read by the GPIOLIB core. Why do you need to repeat this?
> >>>
> >>> My apologies; I had not seen this.
> >>> I'll use gpiochip_get_ngpios() on the next iteration.
> >>
> >> But still why?
> >> https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib.c#L867
> >>
> >> It's called for every driver.
> >>
> >> Maybe it's needed to be refactored to allow fallbacks? Then can the
> >> GPIO MMIO case also be updated?
> >>
> >
> > I guess it's because Hector wants to set an upper limit on the number of GPIOs?
>
> I think Andy is suggesting to rework the gpio-vf610 driver to use
> bgpio_chip struct (it doesn't currently), and then I guess the 'ngpio'
> property gets read automatically if you call bgpio_init().

No, Andy said (and even provided a link to the code) that "ngpios" is
read ALWAYS when a new GPIO chip is registered with the GPIO core.
It's just that it doesn't impose any limits but that could be
addressed with imposing an upper limit in DT bindings maybe?

Bart

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