From: Mirela Rabulea <mirela.rabulea@nxp.com>

According to Rec. ITU-T T.872 (06/2012) 6.5.3
APP14 segment is for color encoding, it contains a transform flag, which
may have values of 0, 1 and 2 and are interpreted as follows:
0 - CMYK for images that are encoded with four components
  - RGB for images that are encoded with three components
1 - An image encoded with three components using YCbCr colour encoding.
2 - An image encoded with four components using YCCK colour encoding.

This is used in imx-jpeg decoder, to distinguish between
YUV444 and RGB24.

Signed-off-by: Mirela Rabulea <mirela.rabulea@nxp.com>
---
Changes in v6:
  Switch variable to lowercase Lp->lp
  Check for "Adobe\0" in Ap1..6
  Make the transform flag an enum
  Removed a change in comment section, a leftover from a previous version
  Thanks Philipp for feedback.

 drivers/media/v4l2-core/v4l2-jpeg.c | 43 +++++++++++++++++++++++++++--
 include/media/v4l2-jpeg.h           | 18 ++++++++++++
 2 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c
index 8947fd95c6f1..d1483e7a775c 100644
--- a/drivers/media/v4l2-core/v4l2-jpeg.c
+++ b/drivers/media/v4l2-core/v4l2-jpeg.c

@@ -45,6 +45,7 @@ MODULE_LICENSE("GPL");
 #define DHP	0xffde	/* hierarchical progression */
 #define EXP	0xffdf	/* expand reference */
 #define APP0	0xffe0	/* application data */
+#define APP14	0xffee	/* application data for colour encoding */
 #define APP15	0xffef
 #define JPG0	0xfff0	/* extensions */
 #define JPG13	0xfffd

@@ -444,8 +445,41 @@ static int jpeg_skip_segment(struct jpeg_stream *stream)
 	return jpeg_skip(stream, len - 2);
 }
 
+/* Rec. ITU-T T.872 (06/2012) 6.5.3 */
+static int jpeg_parse_app14_data(struct jpeg_stream *stream)
+{
+	int ret;
+	int lp;
+	int skip;
+	int tf;
+
+	lp = jpeg_get_word_be(stream);
+	if (lp < 0)
+		return lp;

+	/* Check for "Adobe\0" in Ap1..6 */
+	if (strncmp(stream->curr, "Adobe\0", 6))
+		return -EINVAL;
+
+	/* get to Ap12 */
+	ret = jpeg_skip(stream, 11);
+	if (ret < 0)
+		return -EINVAL;
+
+	tf = jpeg_get_byte(stream);
+	if (tf < 0)
+		return tf;
+
+	skip = lp - 2 - 11;
+	ret = jpeg_skip(stream, skip);
+	if (ret < 0)
+		return -EINVAL;
+	else
+		return tf;
+}
+
 /**
- * jpeg_parse_header - locate marker segments and optionally parse headers
+ * v4l2_jpeg_parse_header - locate marker segments and optionally parse headers
  * @buf: address of the JPEG buffer, should start with a SOI marker
  * @len: length of the JPEG buffer
  * @out: returns marker segment positions and optionally parsed headers

@@ -476,6 +510,9 @@ int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
 	if (marker != SOI)
 		return -EINVAL;
 
+	/* init value to signal if this marker is not present */
+	out->app14_tf = -EINVAL;
+

 	/* loop through marker segments */
 	while ((marker = jpeg_next_marker(&stream)) >= 0) {
 		switch (marker) {

@@ -519,7 +556,9 @@ int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out)
 			ret = jpeg_parse_restart_interval(&stream,
 							&out->restart_interval);
 			break;
-
+		case APP14:
+			out->app14_tf = jpeg_parse_app14_data(&stream);