[PATCH 01/10] video/hdmi: Allow "empty" HDMI infoframes

[Ville Syrjala]

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.

v2: Handle unpack() as well
    Pull the length calculation into a helper

Cc: Shashank Sharma <shashank.sharma at intel.com>
Cc: Andrzej Hajda <a.hajda at samsung.com>
Cc: Thierry Reding <thierry.reding at gmail.com>
Cc: Hans Verkuil <hans.verkuil at cisco.com>
Cc: linux-media at vger.kernel.org
Reviewed-by: Andrzej Hajda <a.hajda at samsung.com> #v1
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/video/hdmi.c | 51 +++++++++++++++++++++++++++++++--------------------
 1 file changed, 31 insertions(+), 20 deletions(-)

diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c
index 1cf907ecded4..111a0ab6280a 100644
--- a/drivers/video/hdmi.c
+++ b/drivers/video/hdmi.c
@@ -321,6 +321,17 @@ int hdmi_vendor_infoframe_init(struct hdmi_vendor_infoframe *frame)
 }
 EXPORT_SYMBOL(hdmi_vendor_infoframe_init);
 
+static int hdmi_vendor_infoframe_length(const 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)
+		return 6;
+	else if (frame->vic != 0 || frame->s3d_struct != HDMI_3D_STRUCTURE_INVALID)
+		return 5;
+	else
+		return 4;
+}
+
 /**
  * hdmi_vendor_infoframe_pack() - write a HDMI vendor infoframe to binary buffer
  * @frame: HDMI infoframe
@@ -341,19 +352,11 @@ 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;
 
-	/* 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
-		frame->length = 5;
+	frame->length = hdmi_vendor_infoframe_length(frame);
 
 	length = HDMI_INFOFRAME_HEADER_SIZE + frame->length;
 
@@ -372,14 +375,16 @@ 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);
@@ -1165,7 +1170,7 @@ hdmi_vendor_any_infoframe_unpack(union hdmi_vendor_any_infoframe *frame,
 
 	if (ptr[0] != HDMI_INFOFRAME_TYPE_VENDOR ||
 	    ptr[1] != 1 ||
-	    (ptr[2] != 5 && ptr[2] != 6))
+	    (ptr[2] != 4 && ptr[2] != 5 && ptr[2] != 6))
 		return -EINVAL;
 
 	length = ptr[2];
@@ -1193,16 +1198,22 @@ hdmi_vendor_any_infoframe_unpack(union hdmi_vendor_any_infoframe *frame,
 
 	hvf->length = length;
 
-	if (hdmi_video_format == 0x1) {
-		hvf->vic = ptr[4];
-	} else if (hdmi_video_format == 0x2) {
+	if (hdmi_video_format == 0x2) {
+		if (length != 5 && length != 6)
+			return -EINVAL;
 		hvf->s3d_struct = ptr[4] >> 4;
 		if (hvf->s3d_struct >= HDMI_3D_STRUCTURE_SIDE_BY_SIDE_HALF) {
-			if (length == 6)
-				hvf->s3d_ext_data = ptr[5] >> 4;
-			else
+			if (length != 6)
 				return -EINVAL;
+			hvf->s3d_ext_data = ptr[5] >> 4;
 		}
+	} else if (hdmi_video_format == 0x1) {
+		if (length != 5)
+			return -EINVAL;
+		hvf->vic = ptr[4];
+	} else {
+		if (length != 4)
+			return -EINVAL;
 	}
 
 	return 0;
-- 
2.13.6