From 9271c0ca573e02a360b636ecd8cb408852f4e9f6 Mon Sep 17 00:00:00 2001
From: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date: Wed, 8 Nov 2017 17:25:04 +0200
Subject: drm/edid: Don't send non-zero YQ in AVI infoframe for HDMI 1.x sinks
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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>
---
include/drm/drm_edid.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
(limited to 'include/drm')
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 1e1908a6b1d6..a992434ded99 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -360,7 +360,8 @@ 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);
/**
* drm_eld_mnl - Get ELD monitor name length in bytes.
--
cgit