video/hdmi: Don't let the user of this API create invalid infoframes

To set the active aspect ratio value in the AVI infoframe today, you not
only have to set the active_aspect field, but also the active_info_valid
bit. Out of the 1 user of this API, we had 100% misuse, forgetting the
_valid bit. This was fixed in:

  Author: Damien Lespiau <damien.lespiau@intel.com>
  Date:   Tue Aug 6 20:32:17 2013 +0100

      drm: Don't generate invalid AVI infoframes for CEA modes

We can do better and derive the _valid bit from the user wanting to set
the active aspect ratio.

v2: Fix multi-lines comment style (Thierry Reding)
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@gmail.com>

drivers/gpu/drm/drm_edid.c

@@ -3259,7 +3259,6 @@ drm_hdmi_avi_infoframe_from_display_mode(struct hdmi_avi_infoframe *frame,
 	frame->video_code = drm_match_cea_mode(mode);
 
 	frame->picture_aspect = HDMI_PICTURE_ASPECT_NONE;
-	frame->active_info_valid = 1;
 	frame->active_aspect = HDMI_ACTIVE_ASPECT_PICTURE;
 
 	return 0;

drivers/video/hdmi.c

@@ -96,7 +96,11 @@ ssize_t hdmi_avi_infoframe_pack(struct hdmi_avi_infoframe *frame, void *buffer,
 
 	ptr[0] = ((frame->colorspace & 0x3) << 5) | (frame->scan_mode & 0x3);
 
-	if (frame->active_info_valid)
+	/*
+	 * Data byte 1, bit 4 has to be set if we provide the active format
+	 * aspect ratio
+	 */
+	if (frame->active_aspect & 0xf)
 		ptr[0] |= BIT(4);
 
 	if (frame->horizontal_bar_valid)

include/linux/hdmi.h

@@ -109,7 +109,6 @@ struct hdmi_avi_infoframe {
 	unsigned char version;
 	unsigned char length;
 	enum hdmi_colorspace colorspace;
-	bool active_info_valid;
 	bool horizontal_bar_valid;
 	bool vertical_bar_valid;
 	enum hdmi_scan_mode scan_mode;