Re: [PATCH v3] spi: gpio: Support 3WIRE high-impedance turn-around

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Thu, Nov 1, 2018 at 10:25 PM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:

> Some devices such as the TPO TPG110 display panel require
> a "high-impedance turn-around", in effect a clock cycle after
> switching the line from output to input mode.
>
> Support this in the GPIO driver to begin with. Other driver
> may implement it if they can, it is unclear if this can
> be achieved with anything else than GPIO bit-banging.
>
> Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> Acked-by: Lorenzo Bianconi <lorenzo.bianconi@xxxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> ChangeLog v2->v3:
> - Drop the device tree parsing (and the device tree bindings)
>   for high-impedance turn-around. This is a client property,
>   so let the drivers using it simply set the flag.

PS Mark: if this is OK now, then I guess it'd be best if I could
get an ACK and apply it to the DRM tree where the panel
driver using the flag will end up, as that will now get a compile-time
dependence on this patch as it sets the flag in the driver
code.

I guess we could also make an immutable branch in the SPI
tree if you think you might e.g. have more new slave flags this
kernel cycle. I have no idea to pull that into drm-misc but I
guess I'd just ask dvetter if I have to.

Yours,
Linus Walleij