[PATCH] drm/i915: set the AVI VIC of the HDMI mode

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

We currently set "0" as the VIC value of the AVI InfoFrames. According
to the specs this should be fine and work for every mode, so to my
point of view we can't consider the current behavior as a bug. The
problem is that  we recently received a bug report (Kernel bug #50371)
from a user that has an AV receiver that gives a black screen for any
mode with VIC set to 0.

So in order to make at least some modes work for him, this patch sets
the correct VIC number when sending AVI InfoFrames. We add a generic
drm function to calculate the VIC number and then call it from the
i915 driver.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=50371
Cc: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/drm_edid.c        |   19 +++++++++++++++++++
 drivers/gpu/drm/drm_modes.c       |    3 ++-
 drivers/gpu/drm/i915/intel_hdmi.c |    2 ++
 include/drm/drm_crtc.h            |    4 +++-
 4 files changed, 26 insertions(+), 2 deletions(-)

Patch applies on top of Daniel's drm-intel-next-queued. I'm not sure who exactly
is going to merge this (Dave or Daniel).

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index fadcd44..c57fc46 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2062,3 +2062,22 @@ int drm_add_modes_noedid(struct drm_connector *connector,
 	return num_modes;
 }
 EXPORT_SYMBOL(drm_add_modes_noedid);
+
+/**
+ * drm_mode_vic - return the CEA-861 VIC of a given mode
+ * @mode: mode
+ *
+ * RETURNS:
+ * The VIC number, 0 in case it's not a CEA-861 mode.
+ */
+uint8_t drm_mode_cea_vic(const struct drm_display_mode *mode)
+{
+	uint8_t i;
+
+	for (i = 0; i < drm_num_cea_modes; i++)
+		if (drm_mode_equal(mode, &edid_cea_modes[i]))
+			return i + 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_mode_cea_vic);
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 59450f3..9ef6750 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -768,7 +768,8 @@ EXPORT_SYMBOL(drm_mode_duplicate);
  * RETURNS:
  * True if the modes are equal, false otherwise.
  */
-bool drm_mode_equal(struct drm_display_mode *mode1, struct drm_display_mode *mode2)
+bool drm_mode_equal(const struct drm_display_mode *mode1,
+		    const struct drm_display_mode *mode2)
 {
 	/* do clock check convert to PICOS so fb modes get matched
 	 * the same */
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 1dcfd5b..eaf70d6 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -340,6 +340,8 @@ static void intel_hdmi_set_avi_infoframe(struct drm_encoder *encoder,
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
 		avi_if.body.avi.YQ_CN_PR |= DIP_AVI_PR_2;
 
+	avi_if.body.avi.VIC = drm_mode_cea_vic(adjusted_mode);
+
 	intel_set_infoframe(encoder, &avi_if);
 }
 
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 3fa18b7..245220e 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -892,7 +892,8 @@ extern void drm_mode_config_init(struct drm_device *dev);
 extern void drm_mode_config_reset(struct drm_device *dev);
 extern void drm_mode_config_cleanup(struct drm_device *dev);
 extern void drm_mode_set_name(struct drm_display_mode *mode);
-extern bool drm_mode_equal(struct drm_display_mode *mode1, struct drm_display_mode *mode2);
+extern bool drm_mode_equal(const struct drm_display_mode *mode1,
+			   const struct drm_display_mode *mode2);
 extern int drm_mode_width(struct drm_display_mode *mode);
 extern int drm_mode_height(struct drm_display_mode *mode);
 
@@ -1053,6 +1054,7 @@ extern struct drm_display_mode *drm_gtf_mode_complex(struct drm_device *dev,
 				int GTF_2C, int GTF_K, int GTF_2J);
 extern int drm_add_modes_noedid(struct drm_connector *connector,
 				int hdisplay, int vdisplay);
+extern uint8_t drm_mode_cea_vic(const struct drm_display_mode *mode);
 
 extern int drm_edid_header_is_valid(const u8 *raw_edid);
 extern bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid);
-- 
1.7.10.4