Re: [PATCH 0/4] Driver for Apple Z2 touchscreens.

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Sasha,

On Tue, Nov 26, 2024 at 09:47:58PM +0100, Sasha Finkelstein via B4 Relay wrote:
> Hi.
> 
> This series adds support for Apple touchscreens using the Z2 protocol.
> Those are used as the primary touchscreen on mobile Apple devices, and for the
> touchbar on laptops using the M-series chips. (T1/T2 laptops have a coprocessor
> in charge of speaking Z2 to the touchbar).
> 
> Originally sent as a RFC at https://lore.kernel.org/all/20230223-z2-for-ml-v1-0-028f2b85dc15@gmail.com/
> The changes since then mostly address the review feedback, but also
> add another machine that has this specific controller.
> 
> The extra gpio needed to be toggled turned out to be a quirk of the
> j293, normal CS is unusable on it, and a gpio has to be used instead.
> (j493 does not have this quirk)

I believe this needs to be done at the SPI controller level. See
"cs-gpiods" property in
Documentation/devicetree/bindings/spi/spi-controller.yaml that, as far
as I understand, allows overriding controller's native CS handling with
a GPIO when needed.

Cc-ing Mark Brown.

Thanks.

-- 
Dmitry