Re: [RESEND PATCH] gpio: pcf857x: restore the initial line state of all pcf lines

From: Linus Walleij
Date: Tue May 31 2016 - 04:40:40 EST

On Fri, May 27, 2016 at 8:35 AM, Kishon Vijay Abraham I <kishon@xxxxxx> wrote:

> The reset values for all the PCF lines are high and hence on
> shutdown we should drive all the lines high in order to
> bring it to the reset state.
> This is actually required since PCF doesn't have a reset
> line and even after warm reset (by invoking "reboot" in
> prompt) the PCF lines maintains it's previous programmed
> state. This becomes a problem if the boards are designed to
> work with the default initial state.
> DRA7XX_evm uses PCF8575 and one of the PCF output lines
> feeds to MMC/SD VDD and this line should be driven high in order
> for the MMC/SD to be detected. This line is modelled as
> regulator and the hsmmc driver takes care of enabling and
> disabling it. In the case of 'reboot', during shutdown path
> as part of it's cleanup process the hsmmc driver disables
> this regulator. This makes MMC *boot* not functional.
> Fix it by driving all the pcf lines high.
> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> Signed-off-by: Sekhar Nori <nsekhar@xxxxxx>

Patch applied.

Linus Walleij