V4L/DVB (7947): videodev: add vidioc_g_std callback.

The default videodev behavior for VIDIOC_G_STD is not correct for all devices.
Add a new callback that drivers can use instead.
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/videodev.c

@@ -1206,11 +1206,15 @@ static int __video_do_ioctl(struct inode *inode, struct file *file,
 	{
 		v4l2_std_id *id = arg;
 
-		*id = vfd->current_norm;
-
-		dbgarg (cmd, "value=%08Lx\n", (long long unsigned) *id);
+		ret = 0;
+		/* Calls the specific handler */
+		if (vfd->vidioc_g_std)
+			ret = vfd->vidioc_g_std(file, fh, id);
+		else
+			*id = vfd->current_norm;
 
-		ret=0;
+		if (!ret)
+			dbgarg(cmd, "value=%08Lx\n", (long long unsigned)*id);
 		break;
 	}
 	case VIDIOC_S_STD:

include/media/v4l2-dev.h

@@ -212,8 +212,9 @@ struct video_device
 	int (*vidioc_streamoff)(struct file *file, void *fh, enum v4l2_buf_type i);
 
 		/* Standard handling
-			G_STD and ENUMSTD are handled by videodev.c
+			ENUMSTD is handled by videodev.c
 		 */
+	int (*vidioc_g_std) (struct file *file, void *fh, v4l2_std_id *norm);
 	int (*vidioc_s_std) (struct file *file, void *fh, v4l2_std_id *norm);
 	int (*vidioc_querystd) (struct file *file, void *fh, v4l2_std_id *a);