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

[Janne Grunau <j@jannau.net>]

On Thu, Nov 28, 2024 at 01:20:09AM +0900, Hector Martin wrote:
> 
> 
> On 2024/11/28 0:29, Hector Martin wrote:
> > 
> > 
> > On 2024/11/27 17:29, Sasha Finkelstein wrote:
> >> On Wed, 27 Nov 2024 at 02:51, Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> >>> 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.
> >>
> >> I have already tried doing that (adding the relevant gpio as cs-gpios
> >> on the controller)
> >> and for some reason none of my attempts worked. Since there is no hardware
> >> documentation, I can't really tell why, could be possible that we need both
> >> native CS and that gpio, could be memory barrier issues somewhere in
> >> the driver core,
> >> but the method above is the only one i could get to work.
> > 
> > Are you sure this isn't just a pinmux problem, i.e. the bootloader
> > initializes the pinmux for hardware CS only on one device and not the other?
> > 
> > See spi3_pins in the DTS in our downstream tree (and the reference from
> > the SPI controller). If the rest of the SPI pins are already working
> > properly you can just try with the CS pin (same index as on the gpio
> > spec). Ideally we'd list the 4 pins, but someone needs to reverse
> > engineer the mapping with m1n1 gpiola since we don't know what it is.
> > 
> > If it really doesn't work with native CS and proper pinmux then cs-gpios
> > on the controller should work. If it doesn't something weird is going on
> > elsewhere. There's only one CS line, needing both makes no sense.
> > 
> 
> Looked into this. The pins are 67=CLK, 68=MOSI, 69=MISO for spi0 on
> t8103 (they should be added to pinctrl even though they are already
> configured by iBoot, ping Janne).

queued for the next revision of my "Add Apple SPI controller and spi-nor
dt nodes" series [0] and imported in the downstream kernel.

thanks
Janne

[0] https://lore.kernel.org/asahi/20241127-asahi-spi-dt-v1-0-907c9447f623@jannau.net/