On Wed, Dec 16, 2020 at 01:46:58AM -0500, Andres Calderon Jaramillo wrote: > On Tue, Dec 15, 2020 at 3:13 PM Ville Syrjälä > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > On Tue, Dec 15, 2020 at 03:06:30PM -0500, Andres Calderon Jaramillo wrote: > > > On Tue, Dec 15, 2020 at 1:01 PM Ville Syrjälä > > > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > > > > > > > On Mon, Dec 14, 2020 at 10:57:03PM +0000, Shankar, Uma wrote: > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > From: andrescj via sendgmr <andrescj@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> > > > > > > On Behalf Of Andres Calderon Jaramillo > > > > > > Sent: Tuesday, December 15, 2020 3:50 AM > > > > > > To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > > > > > Cc: Shankar, Uma <uma.shankar@xxxxxxxxx>; Venkatesh Reddy, Sushma > > > > > > <sushma.venkatesh.reddy@xxxxxxxxx>; seanpaul@xxxxxxxxxxxx; Andres > > > > > > Calderon Jaramillo <andrescj@xxxxxxxxxxxx> > > > > > > Subject: [PATCH] drm/i915/display: Prevent double YUV range correction on HDR > > > > > > planes > > > > > > > > > > > > From: Andres Calderon Jaramillo <andrescj@xxxxxxxxxxxx> > > > > > > > > > > > > Prevent the ICL HDR plane pipeline from performing YUV color range correction > > > > > > twice when the input is in limited range. > > > > > > > > > > > > Before this patch the following could happen: user space gives us a YUV buffer in > > > > > > limited range; per the pipeline in [1], the plane would first go through a "YUV > > > > > > Range correct" stage that expands the range; the plane would then go through > > > > > > the "Input CSC" stage which would also expand the range because > > > > > > icl_program_input_csc() would use a matrix and an offset that assume limited- > > > > > > range input; this would ultimately cause dark and light colors to appear darker > > > > > > and lighter than they should respectively. > > > > > > > > > > > > This is an issue because if a buffer switches between being scanned out and > > > > > > being composited with the GPU, the user will see a color difference. > > > > > > If this switching happens quickly and frequently, the user will perceive this as a > > > > > > flickering. > > > > > > > > > > > > [1] https://01.org/sites/default/files/documentation/intel-gfx-prm-osrc-icllp- > > > > > > vol12-displayengine_0.pdf#page=281 > > > > > > > > > > Change looks good to me, double conversion should not be done. > > > > > Plane input csc coefficients take care of the limited range. > > > > > > > > Might make sense to actually use the hw range correction instead. > > > > Would avoid having to keep around two sets of coefficients. > > > > > > > > Also the question now becomes: How can our tests be passing if > > > > we're doing the range correction twice? > > > > > > > > > > I also considered just removing the limited-range matrix/offsets from > > > icl_program_input_csc(). However, I figured that since the "Input CSC" > > > stage must happen regardless of range correction, maybe it would be a > > > gain to disable the "YUV Range Correction" stage. However, I'm not > > > familiar with the hardware details, so I don't know for sure. I don't > > > feel strongly either way; let me know what you'd prefer. > > > > IIRC we use the fixed function range compression + full range csc > > approach on chv as well. Wouldn't hurt to do the same thing on > > icl+ IMO. > > Sounds good! Thanks for the review. > > > > > > > > > I'm also curious about the testing. How do the tests work? I assume > > > they are in Intel's CI and not open sourced? Do they use the DRM > > > writeback connector (I didn't think this was implemented for i915 > > > yet)? > > > > Tests are here: > > git://anongit.freedesktop.org/xorg/app/intel-gpu-tools > > > > In particular kms_plane/pixel-format tests should rather be failing I > > think. Unless we've relaxed things a bit too much to get the crcs to > > match when the results are close enough. > > > > Nice. I took a look at the tests you referenced. It seems that we may > have just gotten unlucky with the color choice, but I'm not sure why > (I kind of expected to still get a color difference with the current > colors). Hmm. I guess we need to think a bit more about the colors used. > I tried changing the color in [1] to {0.0f, 0.2f, 0.2f}, and > I got "CRC mismatches" failures for multiple formats including NV12, > C8, and YUYV. Interestingly, I had tried something like this multiple > times, and I couldn't get the CRC mismatch at first. I don't know what > changed. Maybe the mode was in a bad state and when I rebooted the > device, it was good. > > Note, with that color change and with this patch, I still get "CRC > mismatches" failures but only for C8. I'm unfamiliar with that format, > but it seems like a different problem. We render the image as RGB332 for C8 so it can only have 2^3 or 2^2 levels. Whereas for the 8bpc reference image we only chop off the results to 5 msbs with the LUT, which gets us 2^5 levels. So the choice of color would have to be constrained to fit the RGB332 limits to get the same output for both. > > [1] https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/third_party/igt-gpu-tools/tests/kms_plane.c;l=383;drc=c8a9aa95e2c5c8d9d39f4f9388a7d602a2e64311 > > > > > > > > > > > > > > Reviewed-by: Uma Shankar <uma.shankar@xxxxxxxxx> > > > > > > > > > > > Signed-off-by: Andres Calderon Jaramillo <andrescj@xxxxxxxxxxxx> > > > > > > --- > > > > > > drivers/gpu/drm/i915/display/intel_display.c | 7 +++++++ > > > > > > 1 file changed, 7 insertions(+) > > > > > > > > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_display.c > > > > > > b/drivers/gpu/drm/i915/display/intel_display.c > > > > > > index 761be8deaa9b..aeea344b06ad 100644 > > > > > > --- a/drivers/gpu/drm/i915/display/intel_display.c > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_display.c > > > > > > @@ -4811,6 +4811,13 @@ u32 glk_plane_color_ctl(const struct intel_crtc_state > > > > > > *crtc_state, > > > > > > plane_color_ctl |= > > > > > > PLANE_COLOR_YUV_RANGE_CORRECTION_DISABLE; > > > > > > } else if (fb->format->is_yuv) { > > > > > > plane_color_ctl |= PLANE_COLOR_INPUT_CSC_ENABLE; > > > > > > + > > > > > > + /* > > > > > > + * Disable the YUV range correction stage because the input CSC > > > > > > + * stage already takes care of range conversion by using separate > > > > > > + * matrices and offsets depending on the color range. > > > > > > + */ > > > > > > + plane_color_ctl |= > > > > > > PLANE_COLOR_YUV_RANGE_CORRECTION_DISABLE; > > > > > > } > > > > > > > > > > > > return plane_color_ctl; > > > > > > -- > > > > > > 2.29.2.684.gfbc64c5ab5-goog > > > > > > > > > > _______________________________________________ > > > > > Intel-gfx mailing list > > > > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx > > > > > > > > -- > > > > Ville Syrjälä > > > > Intel > > > > -- > > Ville Syrjälä > > Intel -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
