[PATCH v7 01/22] drm/edid: fix AVI infoframe aspect ratio handling

[Jani Nikula <jani.nikula@intel.com>]

We try to avoid sending VICs defined in the later specs in AVI
infoframes to sinks that conform to the earlier specs, to not upset
them, and use 0 for the VIC instead. However, we do this detection and
conversion to 0 too early, as we'll need the actual VIC to figure out
the aspect ratio.

In particular, for a mode with 64:27 aspect ratio, 0 for VIC fails the
AVI infoframe generation altogether with -EINVAL.

Separate the VIC lookup from the "filtering", and postpone the
filtering, to use the proper VIC for aspect ratio handling, and the 0
VIC for the infoframe video code as needed.

Reported-by: William Tseng <william.tseng@intel.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/6153
References: https://lore.kernel.org/r/20220920062316.43162-1-william.tseng@intel.com
Cc: <stable@vger.kernel.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 drivers/gpu/drm/drm_edid.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 3841aba17abd..23f7146e6a9b 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -6885,8 +6885,6 @@ static u8 drm_mode_hdmi_vic(const struct drm_connector *connector,
 static u8 drm_mode_cea_vic(const struct drm_connector *connector,
 			   const struct drm_display_mode *mode)
 {
-	u8 vic;
-
 	/*
 	 * HDMI spec says if a mode is found in HDMI 1.4b 4K modes
 	 * we should send its VIC in vendor infoframes, else send the
@@ -6896,13 +6894,18 @@ static u8 drm_mode_cea_vic(const struct drm_connector *connector,
 	if (drm_mode_hdmi_vic(connector, mode))
 		return 0;
 
-	vic = drm_match_cea_mode(mode);
+	return drm_match_cea_mode(mode);
+}
 
-	/*
-	 * HDMI 1.4 VIC range: 1 <= VIC <= 64 (CEA-861-D) but
-	 * HDMI 2.0 VIC range: 1 <= VIC <= 107 (CEA-861-F). So we
-	 * have to make sure we dont break HDMI 1.4 sinks.
-	 */
+/*
+ * Avoid sending VICs defined in HDMI 2.0 in AVI infoframes to sinks that
+ * conform to HDMI 1.4.
+ *
+ * HDMI 1.4 (CTA-861-D) VIC range: [1..64]
+ * HDMI 2.0 (CTA-861-F) VIC range: [1..107]
+ */
+static u8 vic_for_avi_infoframe(const struct drm_connector *connector, u8 vic)
+{
 	if (!is_hdmi2_sink(connector) && vic > 64)
 		return 0;
 
@@ -6978,7 +6981,7 @@ drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe *frame,
 		picture_aspect = HDMI_PICTURE_ASPECT_NONE;
 	}
 
-	frame->video_code = vic;
+	frame->video_code = vic_for_avi_infoframe(connector, vic);
 	frame->picture_aspect = picture_aspect;
 	frame->active_aspect = HDMI_ACTIVE_ASPECT_PICTURE;
 	frame->scan_mode = HDMI_SCAN_MODE_UNDERSCAN;
-- 
2.34.1