Re: [PATCH v2] gpio-sch: set output level after configuration of direction

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Mon, Apr 7, 2014 at 2:20 PM, Alexander Stein
<alexander.stein@xxxxxxxxxxxxxxxxxxxxx> wrote:

> From: Daniel Krueger <daniel.krueger@xxxxxxxxxxxxxxxxxxxxx>
>
> According to the datasheet, writing to the level register has no effect
> when GPIO is programmed as input. Actually the the level register is
> read-only when configured as input. Thus presetting the output level
> before switching to output is _NOT_ possible. Any writes are lost!
> Hence we set the level after configuring the GPIO as output.
> But we cannot prevent a short low pulse if direction is set to high and
> an external  pull-up is connected.
>
> Signed-off-by: Daniel Krueger <daniel.krueger@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx>
> ---
> Changes in v2:
> * Adjusted commited message to make clear that writes are lost when GPIO
> is configured as input.

No further comments, so I have applied this v2 version for v3.16.

Yours,
Linus Walleij
--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html