Re: [PATCH] gpio: serial: max310x: Support open-drain configuration for GPIOs

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Fri, Dec 22, 2017 at 9:29 PM, Jan Kundrát <jan.kundrat@xxxxxxxxx> wrote:

> The push-pull vs. open-drain are the only supported output modes. The
> inputs are always unconditionally equipped with weak pull-downs. That's
> the only mode, so there's probably no point in exporting that. I wonder
> if it's worthwhile to provide a custom dbg_show method to indicate the
> current status of the outputs, though.
>
> This patch and [1] for i2c-gpio together make it possible to bit-bang an
> I2C bus over GPIOs of an UART which is connected via SPI :). Yes, this
> is crazy, but it's fast enough (while on a 26Mhz SPI HW bus with a
> dual-core 1.6GHz CPU) to drive an I2C bus at 200kHz, according to my
> scope.
>
> [1] https://patchwork.ozlabs.org/patch/852591/
>
> Signed-off-by: Jan Kundrát <jan.kundrat@xxxxxxxxx>
> ---
> My suggestion is for this patch to go in via the tty/serial tree; I plan
> to send more patches to this driver (and some of them are alreay in
> tty-next). --jkt

OK Greg can pick this.
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

(Looks very useful for hardware hacking, by the way.)

Yours,
Linus Walleij
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