Re: [PATCH 1/2] cs5535-gpio: add AMD CS5535/CS5536 GPIO driver support

[Andres Salomon]

On Thu, 11 Jun 2009 23:35:55 +0200
Tobias MÃller <Tobias_Mueller@xxxxxxxxx> wrote:

> >> /**
> >> * Some GPIO pins
> >> * Â31-29,23 : reserved (always mask out)
> >> * Â28 Â Â Â : Power Button
> >> * Â26 Â Â Â : PME#
> >> * Â22-16 Â Â: LPC
> >> * Â14,15 Â Â: SMBus
> >> * Â9,8 Â Â Â: UART1
> >> * Â7 Â Â Â Â: PCI INTB
> >> * Â3,4 Â Â Â: UART2/DDC
> >> * Â2 Â Â Â Â: IDE_IRQ0
> >> * Â1 Â Â Â Â: AC_BEEP
> >> * Â0 Â Â Â Â: PCI INTA
> >> *
> >> * If a mask was not specified, be conservative and only allow:
> >> * Â1,2,5,6,10-13,24,25,27
> >> */
> >>
> >> I'll add this in my patch to clear it out.
> >>
> >
> > But why are you being conservative in the first place? ÂIf
> > something's using GPIOs, unless they're unmapped, you should allow
> > it to use them without requiring a boot arg.
> >
> > For example, OLPC uses GPIO 7 for its DCON IRQ. ÂWith the masking
> > scheme, OLPC will need to set that mask from the default. ÂI don't
> > see the point of having the mask at all if other drivers in the
> > kernel are going to be requesting GPIOs (presumably they know what
> > they're doing).
> Hmm... OK, this makes sense. So default mask allow everything exept
> reserved pins and pin 28 (power button).
> 
> I think the mask is quite useful if you've critical things on GPIO
> pins and they should be changeable (especially from userspace and when
> non-root users are allowed to use userspace gpio).

I agree that it would be useful for userspace, just not for
kernelspace.  Is there a way that you can have it only enforce the
mask if the request is coming from userspace?
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