media: v4l2-tpg: add HDMI Video Guard Band test pattern

This inserts 4 pixels of the RGB color 0xab55ab at the left hand side of
the image. This is only done for 3 or 4 byte RGB pixel formats. The HDMI
TMDS encoding of this pixel value equals the Video Guard Band value as
defined by HDMI (see section 5.2.2.1 in the HDMI 1.3 Specification) that
preceeds the first actual pixel of a video line. If an HDMI receiver
doesn't handle this correctly, then it might keep skipping these Video
Guard Band patterns and end up with a shorter video line. So this is a
nice pattern to test with.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/common/v4l2-tpg/v4l2-tpg-core.c

@@ -2402,6 +2402,44 @@ static void tpg_fill_plane_extras(const struct tpg_data *tpg,
 			((params->sav_eav_f ^ vact) << 1) |
 			(hact ^ vact ^ params->sav_eav_f);
 	}
+	if (tpg->insert_hdmi_video_guard_band) {
+		unsigned int i;
+
+		switch (tpg->fourcc) {
+		case V4L2_PIX_FMT_BGR24:
+		case V4L2_PIX_FMT_RGB24:
+			for (i = 0; i < 3 * 4; i += 3) {
+				vbuf[i] = 0xab;
+				vbuf[i + 1] = 0x55;
+				vbuf[i + 2] = 0xab;
+			}
+			break;
+		case V4L2_PIX_FMT_RGB32:
+		case V4L2_PIX_FMT_ARGB32:
+		case V4L2_PIX_FMT_XRGB32:
+		case V4L2_PIX_FMT_BGRX32:
+		case V4L2_PIX_FMT_BGRA32:
+			for (i = 0; i < 4 * 4; i += 4) {
+				vbuf[i] = 0x00;
+				vbuf[i + 1] = 0xab;
+				vbuf[i + 2] = 0x55;
+				vbuf[i + 3] = 0xab;
+			}
+			break;
+		case V4L2_PIX_FMT_BGR32:
+		case V4L2_PIX_FMT_XBGR32:
+		case V4L2_PIX_FMT_ABGR32:
+		case V4L2_PIX_FMT_RGBX32:
+		case V4L2_PIX_FMT_RGBA32:
+			for (i = 0; i < 4 * 4; i += 4) {
+				vbuf[i] = 0xab;
+				vbuf[i + 1] = 0x55;
+				vbuf[i + 2] = 0xab;
+				vbuf[i + 3] = 0x00;
+			}
+			break;
+		}
+	}
 }
 
 static void tpg_fill_plane_pattern(const struct tpg_data *tpg,

include/media/tpg/v4l2-tpg.h

@@ -210,6 +210,7 @@ struct tpg_data {
 	bool				show_square;
 	bool				insert_sav;
 	bool				insert_eav;
+	bool				insert_hdmi_video_guard_band;
 
 	/* Test pattern movement */
 	enum tpg_move_mode		mv_hor_mode;
@@ -591,6 +592,21 @@ static inline void tpg_s_insert_eav(struct tpg_data *tpg, bool insert_eav)
 	tpg->insert_eav = insert_eav;
 }
 
+/*
+ * This inserts 4 pixels of the RGB color 0xab55ab at the left hand side of the
+ * image. This is only done for 3 or 4 byte RGB pixel formats. This pixel value
+ * equals the Video Guard Band value as defined by HDMI (see section 5.2.2.1
+ * in the HDMI 1.3 Specification) that preceeds the first actual pixel. If the
+ * HDMI receiver doesn't handle this correctly, then it might keep skipping
+ * these Video Guard Band patterns and end up with a shorter video line. So this
+ * is a nice pattern to test with.
+ */
+static inline void tpg_s_insert_hdmi_video_guard_band(struct tpg_data *tpg,
+						      bool insert_hdmi_video_guard_band)
+{
+	tpg->insert_hdmi_video_guard_band = insert_hdmi_video_guard_band;
+}
+
 void tpg_update_mv_step(struct tpg_data *tpg);
 
 static inline void tpg_s_mv_hor_mode(struct tpg_data *tpg,