Hi, On 04/08/2026 11:37, Andreas Kemnade wrote:
Some chips need configuration commands to be sent first, before they can send data. TC358762 for example needs PPI_LPTXTIMECNT configured and PPI_STARTPPI set to 1 to be able to transmit anything. To be able to configure such chips, do not send bta sync during writes if no acks are requested. Instead just wait for the packet to be sent to avoid FIFO overflows. There might be more to do about acks, but there seem to be virtually no users of that flag.This came to light when fiddling with the Epson Moverio BT-200 display which consists of 2 TC358762 bridges with SPI funneled through to the unknown display chip. With that patch the bridge can be accessed, Reading back registers works, when the above-mentioned registers are set. In Command-Mode update, there was a nop sent, apparently the most relevant part was the bta sync to actually force low power mode. Video mode panel at OMAP4 (BT-200) and video mode at OMAP5 was tested. Fixes: e70965386353e ("drm/omap: dsi: simplify write function") Signed-off-by: Andreas Kemnade <[email protected]>
Thanks, picking up to drm-misc-next. Tomi
