Hi Fabrizio,
On Fri, Oct 26, 2018 at 9:57 PM Fabrizio Castro
<fabrizio.castro@xxxxxxxxxxxxxx> wrote:
> There are cases when the bootloader configures a pin to work
> as a function rather than GPIO, and other cases when the pin
> is configured as a function at POR.
> This commit makes sure the pin is configured as a GPIO the
> moment we need it to work as an interrupt.
>
> Signed-off-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
> ---
>
> Dear All,
>
> we have got some issues while trying to bring up the interrupt
> line of the HDMI transmitter on the iwg23s, as GP2_29 is configured
> as a function when the kernel starts, and therefore setting up the
> interrupt from the driver won't have the desired effect.
> This patch makes sure the pinctrl driver sets GP2[29] to GP-2-29
> before enabling the interrupt, but it doesn't addresses the
> "direction problem", as in the pin will be a GPIO after calling
> gc->request, but the direction would be whatever was previously
> configured. There could be the option of moving the additional
> code added by this patch to the bottom of function
> gpio_rcar_irq_set_type, but is that going to behave properly on
> every SoC this driver is supporting?
> Is configuring every gpio with direction input while probing
> something that should be looked into to reduce concerns over
> switching from function to GPIO?
Configuring everything to input may cause issues where a GPIO is connected
to the reset line of an external device, and where the bootloader configured the
line to deassert the reset.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
