media: tpg: Add function to return colors' order of test image

Currently there is no method to know the correct order of the colors for
a test image generated by tpg. Write a function that returns a string of
colors' order given a tpg. It returns a NULL pointer in case of test
patterns which do not have a well defined colors' order. Hence add a
NULL check for text in tpg_gen_text().

[hverkuil: white -> White (for consistency)]
Signed-off-by: Kaaira Gupta <kgupta@es.iitr.ac.in>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

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

@@ -1959,12 +1959,14 @@ void tpg_gen_text(const struct tpg_data *tpg, u8 *basep[TPG_MAX_PLANES][2],
 	unsigned step = V4L2_FIELD_HAS_T_OR_B(tpg->field) ? 2 : 1;
 	unsigned div = step;
 	unsigned first = 0;
-	unsigned len = strlen(text);
+	unsigned len;
 	unsigned p;
 
-	if (font8x16 == NULL || basep == NULL)
+	if (font8x16 == NULL || basep == NULL || text == NULL)
 		return;
 
+	len = strlen(text);
+
 	/* Checks if it is possible to show string */
 	if (y + 16 >= tpg->compose.height || x + 8 >= tpg->compose.width)
 		return;
@@ -2006,6 +2008,30 @@ void tpg_gen_text(const struct tpg_data *tpg, u8 *basep[TPG_MAX_PLANES][2],
 }
 EXPORT_SYMBOL_GPL(tpg_gen_text);
 
+const char *tpg_g_color_order(const struct tpg_data *tpg)
+{
+	switch (tpg->pattern) {
+	case TPG_PAT_75_COLORBAR:
+	case TPG_PAT_100_COLORBAR:
+	case TPG_PAT_CSC_COLORBAR:
+	case TPG_PAT_100_HCOLORBAR:
+		return "White, yellow, cyan, green, magenta, red, blue, black";
+	case TPG_PAT_BLACK:
+		return "Black";
+	case TPG_PAT_WHITE:
+		return "White";
+	case TPG_PAT_RED:
+		return "Red";
+	case TPG_PAT_GREEN:
+		return "Green";
+	case TPG_PAT_BLUE:
+		return "Blue";
+	default:
+		return NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(tpg_g_color_order);
+
 void tpg_update_mv_step(struct tpg_data *tpg)
 {
 	int factor = tpg->mv_hor_mode > TPG_MOVE_NONE ? -1 : 1;

include/media/tpg/v4l2-tpg.h

@@ -252,6 +252,7 @@ void tpg_fillbuffer(struct tpg_data *tpg, v4l2_std_id std,
 bool tpg_s_fourcc(struct tpg_data *tpg, u32 fourcc);
 void tpg_s_crop_compose(struct tpg_data *tpg, const struct v4l2_rect *crop,
 		const struct v4l2_rect *compose);
+const char *tpg_g_color_order(const struct tpg_data *tpg);
 
 static inline void tpg_s_pattern(struct tpg_data *tpg, enum tpg_pattern pattern)
 {