[media] v4l2-dv-timings: add support for reduced blanking v2

Added support for reduced blanking version 2 (RB v2) in cvt timings.
Standard specifies a fixed vsync pulse of 8 lines to indicate RB v2
timings. Vertical back porch is fixed at 6 lines and vertical front
porch is remainder of vertical blanking time.

For RB v2, horizontal blanking is fixed at 80 pixels. Horizontal sync
is fixed at 32. All horizontal timing counts (active pixels, front,
back porches) can be specified upto a precision of 1.

RB v2 allows for non standard aspect ratios. In RB v2 vsync does not
indicate aspect ratio. In absence of aspect ratio v4l2_detect_cvt()
cannot calculate image width from image height. Hence extending the
v4l2_detect_cvt() to pass image width in case of RB v2.

Signed-off-by: Prashant Laddha <prladdha@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/media/v4l2-dv-timings.h b/include/media/v4l2-dv-timings.h
index eecd3102a618..e18a653549cd 100644
--- a/include/media/v4l2-dv-timings.h
+++ b/include/media/v4l2-dv-timings.h
@@ -115,6 +115,9 @@ void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
  * @frame_height - the total height of the frame (including blanking) in lines.
  * @hfreq - the horizontal frequency in Hz.
  * @vsync - the height of the vertical sync in lines.
+ * @active_width - active width of image (does not include blanking). This
+ * information is needed only in case of version 2 of reduced blanking.
+ * In other cases, this parameter does not have any effect on timings.
  * @polarities - the horizontal and vertical polarities (same as struct
  *              v4l2_bt_timings polarities).
  * @interlaced - if this flag is true, it indicates interlaced format
@@ -125,7 +128,8 @@ void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
  * in with the found CVT timings.
  */
 bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
-                u32 polarities, bool interlaced, struct v4l2_dv_timings *fmt);
+                unsigned active_width, u32 polarities, bool interlaced,
+                struct v4l2_dv_timings *fmt);
 
 /** v4l2_detect_gtf - detect if the given timings follow the GTF standard
  * @frame_height - the total height of the frame (including blanking) in lines.