On Mon, Oct 07, 2019 at 09:51:27PM +0800, Lee Shawn C wrote: > Refer to EDID 1.3 spec, display FEATURE (byte 18h) bit #0 said > "If this bit is set to 1, the display supports timings based on the > GTF standard using default GTF parameter values". > > And EDID 1.4 spec shows "If bit 0 is set to 0, then the display > is noncontinuous frequency (multi-mode) and is only specified to accept > the video timing formats that are listed in BASE EDID and certain > EXTENSION Blocks. > > When display feature did not support CVT or GFT2 and monitor's EDID version > greater than or equal to "1.2". DRM driver would select GTF as default > for standard timing calculation. It may generated some video timing > that can't display properly by external monitor. > > For example. When driver retrieved "0xD1 0xFC" (FHD, 120Hz) and > "0xD1 0xE8" (FHD, 100Hz) from "Standard Timings". GTF formula > would generate video timing like below. It already over monitor's > spec to cause black screen issue. > "1920x1080" 120 368881 1920 2072 2288 2656 1080 1081 1084 1157 0x0 0x6 > "1920x1080" 100 301992 1920 2072 2280 2640 1080 1081 1084 1144 0x0 0x6 > > v2: Just confirm GTF flag and omit the revision check. > > Cc: Jani Nikula <jani.nik...@intel.com> > Cc: Maarten Lankhorst <maarten.lankho...@linux.intel.com> > Cc: Ville Syrjälä <ville.syrj...@linux.intel.com> > Cc: Adam Jackson <a...@redhat.com> > Cc: Cooper Chiou <cooper.ch...@intel.com> > Signed-off-by: Lee Shawn C <shawn.c....@intel.com> > --- > drivers/gpu/drm/drm_edid.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index 5aee0ebc200e..26eb04820b52 100644 > --- a/drivers/gpu/drm/drm_edid.c > +++ b/drivers/gpu/drm/drm_edid.c > @@ -2193,7 +2193,8 @@ static int standard_timing_level(struct edid *edid) > return LEVEL_CVT; > if (drm_gtf2_hbreak(edid)) > return LEVEL_GTF2; > - return LEVEL_GTF; > + if (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF) > + return LEVEL_GTF;
lgtm. Thanks. Pushed to drm-misc-next. > } > return LEVEL_DMT; > } > -- > 2.17.1 -- Ville Syrjälä Intel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
