[PATCH resend 2/2] gpio: mpc8xxx: don't do RMW on gpdat register when setting value

Tom Rini trini at konsulko.com
Tue Mar 31 21:09:43 CEST 2020

On Tue, Jan 28, 2020 at 12:04:34PM +0000, Rasmus Villemoes wrote:

> The driver correctly handles reading back the value of an output gpio
> by reading from the shadow register for output, and from gpdat for
> inputs.
> Unfortunately, when setting the value of some gpio, we do a RMW cycle
> on the gpdat register without taking the shadow register into account,
> thus accidentally setting other output gpios (at least those whose
> value cannot be read back) to 0 at the same time.
> When changing a gpio from input to output, we still need to make sure
> it initially has the requested value. So, the procedure is
> - update the shadow register
> - compute the new gpdir register
> - write the bitwise and of the shadow and new gpdir register to gpdat
> - write the new gpdir register
> Signed-off-by: Rasmus Villemoes <rasmus.villemoes at prevas.dk>

Applied to u-boot/master, thanks!

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