[media] V4L: soc_mediabus: add a method to obtain the number of samples per pixel

Add a function to calculate the number of samples on the media-bus,
required to retrieve one pixel of a certain format.

Signed-off-by: Alberto Panizzo <maramaopercheseimorto@gmail.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/soc_mediabus.c

@@ -132,6 +132,20 @@ static const struct soc_mbus_pixelfmt mbus_fmt[] = {
 	},
 };
 
+int soc_mbus_samples_per_pixel(const struct soc_mbus_pixelfmt *mf)
+{
+	switch (mf->packing) {
+	case SOC_MBUS_PACKING_NONE:
+	case SOC_MBUS_PACKING_EXTEND16:
+		return 1;
+	case SOC_MBUS_PACKING_2X8_PADHI:
+	case SOC_MBUS_PACKING_2X8_PADLO:
+		return 2;
+	}
+	return -EINVAL;
+}
+EXPORT_SYMBOL(soc_mbus_samples_per_pixel);
+
 s32 soc_mbus_bytes_per_line(u32 width, const struct soc_mbus_pixelfmt *mf)
 {
 	switch (mf->packing) {

include/media/soc_mediabus.h

@@ -61,5 +61,6 @@ struct soc_mbus_pixelfmt {
 const struct soc_mbus_pixelfmt *soc_mbus_get_fmtdesc(
 	enum v4l2_mbus_pixelcode code);
 s32 soc_mbus_bytes_per_line(u32 width, const struct soc_mbus_pixelfmt *mf);
+int soc_mbus_samples_per_pixel(const struct soc_mbus_pixelfmt *mf);
 
 #endif