V4L/DVB (10854): cx18: Correct comments about vertical and horizontal blanking timings

This change only affects comments.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 30 insertions, 20 deletions

diff --git a/drivers/media/video/cx18/cx18-av-core.c b/drivers/media/video/cx18/cx18-av-core.c
index aeeb3cfa3390..21f4be8393b7 100644
--- a/drivers/media/video/cx18/cx18-av-core.c
+++ b/drivers/media/video/cx18/cx18-av-core.c
@@ -292,23 +292,29 @@ void cx18_av_std_setup(struct cx18 *cx)
                  *
                  * vsync:     always 6 half-lines of vsync pulses
                  * vactive:   half lines of active video
-                 * vblank656: half lines, after line 3, of blanked video
-                 * vblank:    half lines, after line 9, of blanked video
+                 * vblank656: half lines, after line 3/mid-266, of blanked video
+                 * vblank:    half lines, after line 9/272, of blanked video
                  *
+                 * As far as I can tell:
                  * vblank656 starts counting from the falling edge of the first
-                 *      vsync pulse (start of line 4)
+                 *      vsync pulse (start of line 4 or mid-266)
                  * vblank starts counting from the after the 6 vsync pulses and
-                 *      6 equalization pulses (start of line 10)
+                 *      6 or 5 equalization pulses (start of line 10 or 272)
                  *
                  * For 525 line systems the driver will extract VBI information
-                 * from lines 10 through 21.  To avoid the EAV RP code from
-                 * toggling at the start of hblank at line 22, where sliced VBI
-                 * data from line 21 is stuffed, also treat line 22 as blanked.
+                 * from lines 10-21 and lines 273-284.
                  */
-                vblank656 = 38; /* lines  4 through  22 */
-                vblank = 26;    /* lines 10 through  22 */
-                vactive = 481;  /* lines 23 through 262.5 */
+                vblank656 = 38; /* lines  4 -  22  &  266 - 284 */
+                vblank = 26;    /* lines 10 -  22  &  272 - 284 */
+                vactive = 481;  /* lines 23 - 263  &  285 - 525 */
 
+                /*
+                 * For a 13.5 Mpps clock and 15,734.26 Hz line rate, a line is
+                 * is 858 pixels = 720 active + 138 blanking.  The Hsync leading
+                 * edge should happen 1.2 us * 13.5 Mpps ~= 16 pixels after the
+                 * end of active video, leaving 122 pixels of hblank to ignore
+                 * before active video starts.
+                 */
                 hactive = 720;
                 hblank = 122;
                 luma_lpf = 1;
diff --git a/drivers/media/video/cx18/cx18-av-core.h b/drivers/media/video/cx18/cx18-av-core.h
index fd0df4151211..2687a2c91ddd 100644
--- a/drivers/media/video/cx18/cx18-av-core.h
+++ b/drivers/media/video/cx18/cx18-av-core.h
@@ -89,16 +89,21 @@ struct cx18_av_state {
 
         /*
          * The VBI slicer starts operating and counting lines, begining at
-         * slicer line count of 1, at D lines after the deassertion of VRESET
-         * This staring field line, S, is 6 or 10 for 625 or 525 line systems.
-         * Sliced ancillary data captured on VBI slicer line M is sent at the
-         * beginning of the next VBI slicer line, VBI slicer line count N = M+1.
-         * Thus when the VBI slicer reports a VBI slicer line number with
-         * ancillary data, the IDID0 byte indicates VBI slicer line N.
-         * The actual field line that the captured data comes from is
+         * slicer line count of 1, at D lines after the deassertion of VRESET.
+         * This staring field line, S, is 6 (& 319) or 10 (& 273) for 625 or 525
+         * line systems respectively.  Sliced ancillary data captured on VBI
+         * slicer line M is inserted after the VBI slicer is done with line M,
+         * when VBI slicer line count is N = M+1.  Thus when the VBI slicer
+         * reports a VBI slicer line number with ancillary data, the IDID0 byte
+         * indicates VBI slicer line N.  The actual field line that the captured
+         * data comes from is
+         *
          * L = M+(S+D-1) = N-1+(S+D-1) = N + (S+D-2).
          *
+         * L is the line in the field, not frame, from which the VBI data came.
+         * N is the line reported by the slicer in the ancillary data.
          * D is the slicer_line_delay value programmed into register 0x47f.
+         * S is 6 for 625 line systems or 10 for 525 line systems
          * (S+D-2) is the slicer_line_offset used to convert slicer reported
          * line counts to actual field lines.
          */
diff --git a/drivers/media/video/cx18/cx18-streams.c b/drivers/media/video/cx18/cx18-streams.c
index ce65cc6c86e8..0932b76b2373 100644
--- a/drivers/media/video/cx18/cx18-streams.c
+++ b/drivers/media/video/cx18/cx18-streams.c
@@ -413,9 +413,8 @@ static void cx18_vbi_setup(struct cx18_stream *s)
                  * 0x90 (Task                         HorizontalBlank)
                  * 0xd0 (Task EvenField               HorizontalBlank)
                  *
-                 * We have set the digitzer to consider the first active line
-                 * as part of VerticalBlank as well so we don't have to look for
-                 * these problem codes nor lose the last line of sliced data.
+                 * We have set the digitzer such that we don't have to worry
+                 * about these problem codes.
                  */
                 data[4] = 0xB0F0B0F0;
                 /*