Hi, On Fri, Apr 7, 2023 at 9:46 AM Nikita Travkin <nikita@xxxxxxx> wrote: > > > HPD might very well be hooked up on your board, but the current Linux > > ti-sn65dsi86 driver does not look at its own HPD line because it's > > actually slower than just pretending that HPD isn't there. On trogdor > > boards we ended up routing HPD to a GPIO. > > > > Oh, this makes so much sense then! The line is hooked up on > the board indeed and I remember being confused why trogdor boards > don't use it. > > I will try to add the suggestions (annotating the reason) > and verify that it works, would prefer the panel power to be > gated when possible. I hope this would also fix the initial > EDID reading issues I occasionally have and carry a hack for > as of now... > > Thank you a lot for this insight! > > Nikita > > > I guess your other option would be to implement HPD support in > > ti-sn65dsi86. That would probably be an overall slower boot for you, > > but is technically more correct. In the past people have posted up > > patches to get ti-sn65dsi86 working as a full DP port and they added > > HPD support for that, but none of those patch series ever go to the > > point of landing... Yeah, see the big comment in ti_sn65dsi86_enable_comms(). Actually, looking at how the code has evolved in the meantime, you could probably get away with: 1. Making sure you have an "hpd-absent-delay-ms" in the device tree for the panel. 2. Implement "wait_hpd_asserted" in ti-sn65dsi86 to simply be a msleep with the passed in delay. Then I think you don't need "no-hpd" anywhere which keeps the device tree pretty. -Doug
