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15 Dec 2020 12:13:17 -0800 Received: by stinkbox (sSMTP sendmail emulation); Tue, 15 Dec 2020 22:13:16 +0200 Date: Tue, 15 Dec 2020 22:13:16 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Andres Calderon Jaramillo Message-ID: References: <20201214221934.2478240-1-andrescj@google.com> <9448bc8ea67a49d6a1ebf208824e5472@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Patchwork-Hint: comment Subject: Re: [Intel-gfx] [PATCH] drm/i915/display: Prevent double YUV range correction on HDR planes X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andres Calderon Jaramillo , "intel-gfx@lists.freedesktop.org" , "seanpaul@chromium.org" , "Venkatesh Reddy, Sushma" Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Tue, Dec 15, 2020 at 03:06:30PM -0500, Andres Calderon Jaramillo wrote: > On Tue, Dec 15, 2020 at 1:01 PM Ville Syrj=E4l=E4 > wrote: > > > > On Mon, Dec 14, 2020 at 10:57:03PM +0000, Shankar, Uma wrote: > > > > > > > > > > -----Original Message----- > > > > From: andrescj via sendgmr > > > > On Behalf Of Andres Calderon Jaramillo > > > > Sent: Tuesday, December 15, 2020 3:50 AM > > > > To: intel-gfx@lists.freedesktop.org > > > > Cc: Shankar, Uma ; Venkatesh Reddy, Sushma > > > > ; seanpaul@chromium.org; Andres > > > > Calderon Jaramillo > > > > Subject: [PATCH] drm/i915/display: Prevent double YUV range correct= ion on HDR > > > > planes > > > > > > > > From: Andres Calderon Jaramillo > > > > > > > > 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 th= rough a "YUV > > > > Range correct" stage that expands the range; the plane would then g= o through > > > > the "Input CSC" stage which would also expand the range because > > > > icl_program_input_csc() would use a matrix and an offset that assum= e limited- > > > > range input; this would ultimately cause dark and light colors to a= ppear 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 per= ceive this as a > > > > flickering. > > > > > > > > [1] https://01.org/sites/default/files/documentation/intel-gfx-prm-= osrc-icllp- > > > > vol12-displayengine_0.pdf#page=3D281 > > > > > > 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. > = > 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. > = > > > > > > Reviewed-by: Uma Shankar > > > > > > > Signed-off-by: Andres Calderon Jaramillo > > > > --- > > > > 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_c= rtc_state > > > > *crtc_state, > > > > plane_color_ctl |=3D > > > > PLANE_COLOR_YUV_RANGE_CORRECTION_DISABLE; > > > > } else if (fb->format->is_yuv) { > > > > plane_color_ctl |=3D PLANE_COLOR_INPUT_CSC_ENABLE; > > > > + > > > > + /* > > > > + * Disable the YUV range correction stage because the i= nput CSC > > > > + * stage already takes care of range conversion by usin= g separate > > > > + * matrices and offsets depending on the color range. > > > > + */ > > > > + plane_color_ctl |=3D > > > > PLANE_COLOR_YUV_RANGE_CORRECTION_DISABLE; > > > > } > > > > > > > > return plane_color_ctl; > > > > -- > > > > 2.29.2.684.gfbc64c5ab5-goog > > > > > > _______________________________________________ > > > Intel-gfx mailing list > > > Intel-gfx@lists.freedesktop.org > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx > > > > -- > > Ville Syrj=E4l=E4 > > Intel -- = Ville Syrj=E4l=E4 Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx