[PATCH v2 2/4] gpio: aspeed: Add "Read Data" register to read the write latch

[Joel Stanley]

On 18 June 2018 at 14:23, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
> The Aspeed GPIO hardware has a quirk: the value register, for an
> output GPIO, doesn't contain the last value written (the write
> latch content) but the sampled input value.
>
> This means that when reading back shortly after writing, you can
> get an incorrect value as the input value is delayed by a few
> synchronizers.
>
> The HW supports a separate read-only register "Data Read Register"
> which allows you to read the write latch instead.
>
> This adds the definition for it, and uses it for the initial
> population of the GPIO value cache. It will be used more in
> subsequent patches.
> can be
>
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

Reviewed-by: Joel Stanley <joel at jms.id.au>