On Tue, 31 Oct 2017 12:32:58 -0700
Eric Anholt <eric@xxxxxxxxxx> wrote:
> It turns out that I had just mistaken what type of write the register
> writes were supposed to be, using DCS instead of generic long writes.
>
> Switching to transactions instead of using the atmel as a bridge also
> seems to resolve the sparkling pixels problem I've had.
>
> Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
> Fixes: 2f733d6194bd ("drm/panel: Add support for the Raspberry Pi 7" Touchscreen.")
Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 14 +-------------
> 1 file changed, 1 insertion(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> index d964d454e4ae..2c9c9722734f 100644
> --- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
> @@ -238,12 +238,6 @@ static void rpi_touchscreen_i2c_write(struct rpi_touchscreen *ts,
>
> static int rpi_touchscreen_write(struct rpi_touchscreen *ts, u16 reg, u32 val)
> {
> -#if 0
> - /* The firmware uses LP DSI transactions like this to bring up
> - * the hardware, which should be faster than using I2C to then
> - * pass to the Toshiba. However, I was unable to get it to
> - * work.
> - */
> u8 msg[] = {
> reg,
> reg >> 8,
> @@ -253,13 +247,7 @@ static int rpi_touchscreen_write(struct rpi_touchscreen *ts, u16 reg, u32 val)
> val >> 24,
> };
>
> - mipi_dsi_dcs_write_buffer(ts->dsi, msg, sizeof(msg));
> -#else
> - rpi_touchscreen_i2c_write(ts, REG_WR_ADDRH, reg >> 8);
> - rpi_touchscreen_i2c_write(ts, REG_WR_ADDRL, reg);
> - rpi_touchscreen_i2c_write(ts, REG_WRITEH, val >> 8);
> - rpi_touchscreen_i2c_write(ts, REG_WRITEL, val);
> -#endif
> + mipi_dsi_generic_write(ts->dsi, msg, sizeof(msg));
>
> return 0;
> }
--
Boris Brezillon, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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