media: uvcvideo: Set the colorspace as sRGB if undefined

Never return V4L2_COLORSPACE_DEFAULT. From the standard:

"""
In the absence of this descriptor, or in the case of
“Unspecified” values within the descriptor, color matching
defaults will be assumed. The color matching defaults are
compliant with sRGB since the BT.709 transfer function and
the sRGB transfer function are very similar.
"""
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Tested-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/usb/uvc/uvc_driver.c

@@ -256,7 +256,7 @@ static struct uvc_format_desc *uvc_format_by_guid(const u8 guid[16])
 static enum v4l2_colorspace uvc_colorspace(const u8 primaries)
 {
 	static const enum v4l2_colorspace colorprimaries[] = {
-		V4L2_COLORSPACE_DEFAULT,  /* Unspecified */
+		V4L2_COLORSPACE_SRGB,  /* Unspecified */
 		V4L2_COLORSPACE_SRGB,
 		V4L2_COLORSPACE_470_SYSTEM_M,
 		V4L2_COLORSPACE_470_SYSTEM_BG,
@@ -267,7 +267,7 @@ static enum v4l2_colorspace uvc_colorspace(const u8 primaries)
 	if (primaries < ARRAY_SIZE(colorprimaries))
 		return colorprimaries[primaries];
 
-	return V4L2_COLORSPACE_DEFAULT;  /* Reserved */
+	return V4L2_COLORSPACE_SRGB;  /* Reserved */
 }
 
 static enum v4l2_xfer_func uvc_xfer_func(const u8 transfer_characteristics)
@@ -769,6 +769,8 @@ static int uvc_parse_format(struct uvc_device *dev,
 
 		buflen -= buffer[0];
 		buffer += buffer[0];
+	} else {
+		format->colorspace = V4L2_COLORSPACE_SRGB;
 	}
 
 	return buffer - start;