[U-Boot] [PATCH] gpio: mxc_gpio: Fix gpio_get_value() when the GPIO is an output

[Eric Bénard]

Le Sun, 29 Sep 2013 14:48:32 -0300,
Otavio Salvador <otavio at ossystems.com.br> a écrit :

> On Sun, Sep 29, 2013 at 2:09 PM, Eric Bénard <eric at eukrea.com> wrote:
> > Hi Benoît,
> >
> > Le Sun, 29 Sep 2013 15:21:52 +0200 (CEST),
> > Benoît Thébaudeau <benoit.thebaudeau at advansee.com> a écrit :
> >> Why is this required? Is it because there is a different behavior of the PSR
> >> register on one of the i.MXs?
> >>
> >> See my commit message here:
> >> http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=commitdiff;h=5dafa4543c399d329c7b01df1afa98437861cac0
> >>
> >> In case the registers are configured to output some level on a GPIO but there is
> >> a level conflict with other hardware, the general assumption about
> >> gpio_get_value() would probably be that it returns the actual GPIO level, not
> >> the level that the registers try to apply. For the latter, another function
> >> accessing DR could be implemented.
> >>
> > you are right and if that works in the kernel, that should also work
> > in u-boot. It would be interesting to know if the original patch was
> > really fixing a problem as it would be surprising that setting the pin
> > as an input could fix the level sampling problem reliably : Otavio was
> > that tested on real hardware ?
> 
> Yes; it did.
> 
> Both my original patch (setting it as input) and Fabio's one checking
> the other register when in output worked fine.
> 
on which CPU is that ?
It's strange reading PSR works in the kernel and not in u-boot.

Eric