Hi everyone,

Am Dienstag, 28. Februar 2023, 09:46:27 CET schrieb Marco Felsch:

Hi Dario,

On 23-02-28, Dario Binacchi wrote:

quoted

Hi Stefan,

On Mon, Feb 27, 2023 at 6:52 PM Stefan Wahren [off-list ref] 

wrote:

quoted

quoted

Hi Dario,

Am 26.02.23 um 21:53 schrieb Dario Binacchi:

quoted

Since commit 502df79b860563d7 ("gpiolib: Warn on drivers still using
static
gpiobase allocation"), one or more warnings are printed during boot on
systems where static allocation of GPIO base is used:

[    0.136834] gpio gpiochip0: Static allocation of GPIO base is
deprecated, use dynamic allocation. [    0.142753] gpio gpiochip1:
Static allocation of GPIO base is deprecated, use dynamic allocation.
[    0.148452] gpio gpiochip2: Static allocation of GPIO base is
deprecated, use dynamic allocation. [    0.154341] gpio gpiochip3:
Static allocation of GPIO base is deprecated, use dynamic allocation.
[    0.160097] gpio gpiochip4: Static allocation of GPIO base is
deprecated, use dynamic allocation.

So let's follow the suggestion and use dynamic allocation.

i understand the motivation of avoiding these warnings.

AFAIK the MXS platform is older than the dynamic allocation of GPIO
base. In the perfect world all applications has been migrated to
libgpiod / chardev GPIO. But i'm really concerned this hasn't happend
yet, at least for this platform. So i believe this change break
applications, since it affects userspace.

Thanks for your explanations.

There was also a lengthly discussion here:

https://lore.kernel.org/all/20230120104647.nwki4silrtd7bt3w@pengutronix.de/ (local)

quoted

Do you think it makes sense to use a Kconfig option to enable/disable
the dynamic allocation of GPIO base?

What we could do is to check the GPIO_SYSFS kconfig symbol. If this is
enabled we should keep the current behaviour to not break the uAPI else
we can go with the dynamic numbering. What we should avoid is a new
Kconfig symbol.

Even that is only half of the truth. Apparently this is crucial for 
GPIO_SYSFS, but even without sysfs it affects the order of the character 
devices, which might break userspace. The main open issue is, whether GPIO 
aliases shall be supported or not, see see [1] and [2].
Once this is clear, the switch to dynamic base can be done.

Best regards,
Alexander

[1] https://lore.kernel.org/linux-gpio/20230215092421.143199-1-alexander.stein@ew.tq-group.com/T/#u (local)
[2] https://lore.kernel.org/linux-gpio/5941337.lOV4Wx5bFT@steina-w/T/ (local)
#m2a74777fc4031b7f6f30ac1dcf65b20e7d3f8f12

Regards,
  Marco

quoted

As done, if I'm not mistaken, in commit 80d34260f36c6 ("pinctrl:
renesas: gpio: Use dynamic GPIO base if no function GPIOs")?
With legacy support enabled by default, but the ability to try out the
latest dynamic allocation functionality.

Thanks and regards,
Dario

quoted

Best regards

quoted

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---

  drivers/gpio/gpio-mxs.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mxs.c b/drivers/gpio/gpio-mxs.c
index 7f59e5d936c2..b48a7c1fb7c1 100644
--- a/drivers/gpio/gpio-mxs.c
+++ b/drivers/gpio/gpio-mxs.c

@@ -330,7 +330,7 @@ static int mxs_gpio_probe(struct platform_device

*pdev)

      port->gc.to_irq = mxs_gpio_to_irq;
      port->gc.get_direction = mxs_gpio_get_direction;

-     port->gc.base = port->id * 32;
+     port->gc.base = -1;

      err = gpiochip_add_data(&port->gc, port);
      if (err)

-- 
TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany
Amtsgericht München, HRB 105018
Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider
http://www.tq-group.com/



_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel