diff options
| author | Prashant Laddha <prladdha@cisco.com> | 2015-04-22 17:32:34 (GMT) |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@osg.samsung.com> | 2015-05-01 10:14:02 (GMT) |
| commit | f67476589afc9a4a48bc342f1b5f505b508bd1ff (patch) | |
| tree | dc402509bceed35ddf256a3dbda258d7702faf8e | |
| parent | ef403bcaf16b704b772cf33cc2871fb8693d3bb3 (diff) | |
| download | linux-f67476589afc9a4a48bc342f1b5f505b508bd1ff.tar.xz | |
[media] v4l2-dv-timings: fix rounding error in vsync_bp calculation
Changed the rounding offsets used in vsync_bp calculation in cvt and
gtf timings. The results for vsync_bp should now match with results
from timing generator spreadsheets for cvt and gtf standards.
In the vsync_bp calculation for cvt, always round down the value of
(CVT_MIN_VSYNC_BP / h_period_est) and then add 1. It thus, reflects
the equation used in timing generator spreadsheet. Using 1999999 as
rounding offset, could pontentially lead to bumping up the vsync_bp
value by extra 1.
In the vsync_bp calculations for gtf, instead of round up or round
down, round the (CVT_MIN_VSYNC_BP / h_period_est) to the nearest
integer.
Thanks to Martin Bugge <marbugge@cisco.com> for validating with
standards and suggestions on equations.
Cc: Martin Bugge <marbugge@cisco.com>
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>
| -rw-r--r-- | drivers/media/v4l2-core/v4l2-dv-timings.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/media/v4l2-core/v4l2-dv-timings.c b/drivers/media/v4l2-core/v4l2-dv-timings.c index c0e9638..32aa25f 100644 --- a/drivers/media/v4l2-core/v4l2-dv-timings.c +++ b/drivers/media/v4l2-core/v4l2-dv-timings.c @@ -368,14 +368,14 @@ bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync, /* Vertical */ if (reduced_blanking) { v_fp = CVT_RB_V_FPORCH; - v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 1999999) / 1000000; + v_bp = (CVT_RB_MIN_V_BLANK * hfreq) / 1000000 + 1; v_bp -= vsync + v_fp; if (v_bp < CVT_RB_MIN_V_BPORCH) v_bp = CVT_RB_MIN_V_BPORCH; } else { v_fp = CVT_MIN_V_PORCH_RND; - v_bp = (CVT_MIN_VSYNC_BP * hfreq + 1999999) / 1000000 - vsync; + v_bp = (CVT_MIN_VSYNC_BP * hfreq) / 1000000 + 1 - vsync; if (v_bp < CVT_MIN_V_BPORCH) v_bp = CVT_MIN_V_BPORCH; @@ -529,7 +529,8 @@ bool v4l2_detect_gtf(unsigned frame_height, /* Vertical */ v_fp = GTF_V_FP; - v_bp = (GTF_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync; + + v_bp = (GTF_MIN_VSYNC_BP * hfreq + 500000) / 1000000 - vsync; image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1; if (aspect.numerator == 0 || aspect.denominator == 0) { |