On Wed, 11 Jan 2017, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > On Wed, Jan 11, 2017 at 05:09:16PM +0200, Jani Nikula wrote: >> On Tue, 10 Jan 2017, Manasi Navare <manasi.d.navare@xxxxxxxxx> wrote: >> > Hi All, >> > >> > We are seeing CRC check failures in some of the 18bpp video pattern >> > DP Compliance tests causing the tests to fail. On further investigation, it is >> > rootcaused to dithering that the i915 driver enables in case of 18bpp pipe >> > configuration that messes up the CRC and causes the test to fail. >> >> The CTS spec actually accounts for CRC failures caused by dithering and >> color space conversions. See section 3.2.1. However, it would be >> preferrable to be able to automate this. >> >> > Some of the approaches that can solve this problem are: >> > 1. Add a new method in intel_dp.c to request the compliance test state. >> > Call this new method in intel_display.c to not enable dithering during a >> > compliance test. Issue with this is it makes the general portion of the driver >> > compliance aware. >> > >> > 2. Move the dithering enable to compute_config methods in all encoder source >> > files. Issue: Lot of duplicate code and DP is the only encoder that uses 18bpc. >> > >> > 3. Disable dithering at all times in the driver. However this can cause image >> > quality issue with 8bpc plane and 6 bit pipe. >> > >> > Any suggestions on which approach can be implemented in order to pass >> > compliance? >> >> I can't find any mention in the specs that we couldn't enable/disable >> dithering on the fly. It's PIPE_MISC for BDW+ and PIPE_CONF for the >> rest. So I'm wondering about doing... >> >> 4. Disable dithering at intel_dp_sink_crc_start() and enable it again >> (according to config->dither) at intel_dp_sink_crc_stop(). It's >> similar to the hsw_disable_ips() and hsw_enable_ips() calls, but >> would have to cover more platforms. >> >> Ville, thoughts on changing dithering on the fly? > > Should be fine I think. > > BTW see > https://lists.freedesktop.org/archives/intel-gfx/2016-December/115186.html > if you intend to add more crc workaround type of things. There I'm > changing the IPS w/a to force a full modeset because it was the easiest > way to do things, and the current thing is just broken. I think forcing a modeset for sink crc would be rather annoying. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
