RE: [RFC] gpio: rcar: Request GPIO before enabling interrupt

[Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>]

Hello Geert,

Thank you for your feedback!

> Subject: Re: [RFC] gpio: rcar: Request GPIO before enabling interrupt
>
> 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.

I am going to stay away from this then.

Thanks,
Fab

>
> 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



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