[PATCH 1/2] video/hdmi: Allow "empty" HDMI infoframes

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

HDMI 2.0 Appendix F suggest that we should keep sending the infoframe
when switching from 3D to 2D mode, even if the infoframe isn't strictly
necessary (ie. not needed to transmit the VIC or stereo information).
This is a workaround against some sinks that fail to realize that they
should switch from 3D to 2D mode when the source stop transmitting
the infoframe.

Cc: Shashank Sharma <shashank.sharma at intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/video/hdmi.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c
index 1cf907ecded4..af0c8dad29eb 100644
--- a/drivers/video/hdmi.c
+++ b/drivers/video/hdmi.c
@@ -341,10 +341,6 @@ ssize_t hdmi_vendor_infoframe_pack(struct hdmi_vendor_infoframe *frame,
 	u8 *ptr = buffer;
 	size_t length;
 
-	/* empty info frame */
-	if (frame->vic == 0 && frame->s3d_struct == HDMI_3D_STRUCTURE_INVALID)
-		return -EINVAL;
-
 	/* only one of those can be supplied */
 	if (frame->vic != 0 && frame->s3d_struct != HDMI_3D_STRUCTURE_INVALID)
 		return -EINVAL;
@@ -352,8 +348,10 @@ ssize_t hdmi_vendor_infoframe_pack(struct hdmi_vendor_infoframe *frame,
 	/* for side by side (half) we also need to provide 3D_Ext_Data */
 	if (frame->s3d_struct >= HDMI_3D_STRUCTURE_SIDE_BY_SIDE_HALF)
 		frame->length = 6;
-	else
+	else if (frame->vic != 0 || frame->s3d_struct != HDMI_3D_STRUCTURE_INVALID)
 		frame->length = 5;
+	else
+		frame->length = 4;
 
 	length = HDMI_INFOFRAME_HEADER_SIZE + frame->length;
 
@@ -372,14 +370,16 @@ ssize_t hdmi_vendor_infoframe_pack(struct hdmi_vendor_infoframe *frame,
 	ptr[5] = 0x0c;
 	ptr[6] = 0x00;
 
-	if (frame->vic) {
-		ptr[7] = 0x1 << 5;	/* video format */
-		ptr[8] = frame->vic;
-	} else {
+	if (frame->s3d_struct != HDMI_3D_STRUCTURE_INVALID) {
 		ptr[7] = 0x2 << 5;	/* video format */
 		ptr[8] = (frame->s3d_struct & 0xf) << 4;
 		if (frame->s3d_struct >= HDMI_3D_STRUCTURE_SIDE_BY_SIDE_HALF)
 			ptr[9] = (frame->s3d_ext_data & 0xf) << 4;
+	} else if (frame->vic) {
+		ptr[7] = 0x1 << 5;	/* video format */
+		ptr[8] = frame->vic;
+	} else {
+		ptr[7] = 0x0 << 5;	/* video format */
 	}
 
 	hdmi_infoframe_set_checksum(buffer, length);
-- 
2.13.0