On Thu, Jan 12, 2017 at 03:41:07PM -0800, Rodrigo Vivi wrote: > On Thu, Jan 12, 2017 at 3:30 PM, Manasi Navare > <manasi.d.navare@xxxxxxxxx> wrote: > > On Thu, Jan 12, 2017 at 12:32:09PM +0200, Jani Nikula wrote: > >> 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. > >> >> > > > > intel_dp_sink_crc_start() gets called only through the debugfs interface. > > Do you really use this sink crc for the compliance tests? > Or are you talking about some other CRC level check like in the compliance box? > Exactly, DPR 120 does a CRC check on the pixel values during the 18bpp video pattern tests. So we need to disable dithering before that modeset or during intel_modeset_pipe_config() where it sets pipe_config->dither to true. So I am not sure I understand how disabling the dithering at intel_dp_sink_crc_start() would help. Manasi > > If we disable dithering here, DPR 120 which is calculating the CRC of the > > pixels on the rendered video pattern would already have dithering enabled on it. > > So how will this solve our issue of CRC failures in case of 18bpc test? > > > > Manasi > > > > > >> >> 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 > > > > -- > Rodrigo Vivi > Blog: http://blog.vivi.eng.br _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
