drm/edid: Don't send non-zero YQ in AVI infoframe for HDMI 1.x sinks
Apparently some sinks look at the YQ bits even when receiving RGB,
and they get somehow confused when they see a non-zero YQ value.
So we can't just blindly follow CEA-861-F and set YQ to match the
RGB range.
Unfortunately there is no good way to tell whether the sink
designer claims to have read CEA-861-F. The CEA extension block
revision number has generally been stuck at 3 since forever,
and even a very recently manufactured sink might be based on
an old design so the manufacturing date doesn't seem like
something we can use. In lieu of better information let's
follow CEA-861-F only for HDMI 2.0 sinks, since HDMI 2.0 is
based on CEA-861-F. For HDMI 1.x sinks we'll always set YQ=0.
The alternative would of course be to always set YQ=0. And if
we ever encounter a HDMI 2.0+ sink with this bug that's what
we'll probably have to do.
Cc: stable@vger.kernel.org
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Neil Kownacki <njkkow@gmail.com>
Reported-by: Neil Kownacki <njkkow@gmail.com>
Tested-by: Neil Kownacki <njkkow@gmail.com>
Fixes: fcc8a22cc905 ("drm/edid: Set YQ bits in the AVI infoframe according to CEA-861-F")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101639
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171108152504.12596-1-ville.syrjala@linux.intel.com
Acked-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 6bb6337..fc7946e 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4809,7 +4809,8 @@ void
drm_hdmi_avi_infoframe_quant_range(struct hdmi_avi_infoframe *frame,
const struct drm_display_mode *mode,
enum hdmi_quantization_range rgb_quant_range,
- bool rgb_quant_range_selectable)
+ bool rgb_quant_range_selectable,
+ bool is_hdmi2_sink)
{
/*
* CEA-861:
@@ -4833,8 +4834,15 @@ drm_hdmi_avi_infoframe_quant_range(struct hdmi_avi_infoframe *frame,
* YQ-field to match the RGB Quantization Range being transmitted
* (e.g., when Limited Range RGB, set YQ=0 or when Full Range RGB,
* set YQ=1) and the Sink shall ignore the YQ-field."
+ *
+ * Unfortunate certain sinks (eg. VIZ Model 67/E261VA) get confused
+ * by non-zero YQ when receiving RGB. There doesn't seem to be any
+ * good way to tell which version of CEA-861 the sink supports, so
+ * we limit non-zero YQ to HDMI 2.0 sinks only as HDMI 2.0 is based
+ * on on CEA-861-F.
*/
- if (rgb_quant_range == HDMI_QUANTIZATION_RANGE_LIMITED)
+ if (!is_hdmi2_sink ||
+ rgb_quant_range == HDMI_QUANTIZATION_RANGE_LIMITED)
frame->ycc_quantization_range =
HDMI_YCC_QUANTIZATION_RANGE_LIMITED;
else