Patch "drm/edid: Don't send non-zero YQ in AVI infoframe for HDMI 1.x sinks" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    drm/edid: Don't send non-zero YQ in AVI infoframe for HDMI 1.x sinks

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-edid-don-t-send-non-zero-yq-in-avi-infoframe-for-hdmi-1.x-sinks.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 9271c0ca573e02a360b636ecd8cb408852f4e9f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <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
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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From: Ville Syrjälä <ville.syrjala@linux.intel.com>

commit 9271c0ca573e02a360b636ecd8cb408852f4e9f6 upstream.

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: 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/drm_edid.c        |   12 ++++++++++--
 drivers/gpu/drm/i915/intel_hdmi.c |    3 ++-
 drivers/gpu/drm/vc4/vc4_hdmi.c    |    3 ++-
 include/drm/drm_edid.h            |    3 ++-
 4 files changed, 16 insertions(+), 5 deletions(-)

--- 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(struc
 	 *  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
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -481,7 +481,8 @@ static void intel_hdmi_set_avi_infoframe
 					   crtc_state->limited_color_range ?
 					   HDMI_QUANTIZATION_RANGE_LIMITED :
 					   HDMI_QUANTIZATION_RANGE_FULL,
-					   intel_hdmi->rgb_quant_range_selectable);
+					   intel_hdmi->rgb_quant_range_selectable,
+					   is_hdmi2_sink);
 
 	/* TODO: handle pixel repetition for YCBCR420 outputs */
 	intel_write_infoframe(encoder, crtc_state, &frame);
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -433,7 +433,8 @@ static void vc4_hdmi_set_avi_infoframe(s
 					   vc4_encoder->limited_rgb_range ?
 					   HDMI_QUANTIZATION_RANGE_LIMITED :
 					   HDMI_QUANTIZATION_RANGE_FULL,
-					   vc4_encoder->rgb_range_selectable);
+					   vc4_encoder->rgb_range_selectable,
+					   false);
 
 	vc4_hdmi_write_infoframe(encoder, &frame);
 }
--- 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.


Patches currently in stable-queue which might be from ville.syrjala@linux.intel.com are

queue-4.14/drm-edid-don-t-send-non-zero-yq-in-avi-infoframe-for-hdmi-1.x-sinks.patch
queue-4.14/drm-vblank-fix-flip-event-vblank-count.patch
queue-4.14/drm-vblank-tune-drm_crtc_accurate_vblank_count-warn-down-to-a-debug.patch