diff options
| author | Martin Bugge <marbugge@cisco.com> | 2013-08-14 07:58:38 (GMT) |
|---|---|---|
| committer | Mauro Carvalho Chehab <m.chehab@samsung.com> | 2013-08-24 07:19:08 (GMT) |
| commit | c3e75c7d5e203b6d1d16519bef8571b5d228b7fe (patch) | |
| tree | 66b42a19890ad31ad6ca612b3f465ed654048ba8 | |
| parent | 1056e4388b0454917a512618c8416a98628fc9ce (diff) | |
| download | linux-c3e75c7d5e203b6d1d16519bef8571b5d228b7fe.tar.xz | |
[media] v4l2-dv-timings: fix CVT calculation
This patch fixes two errors that caused incorrect format detections:
The first bug is in the calculation of the vertical backporch: the combined
period of vsync and backporch must *exceed* a certain minimum value, and not
be equal to it.
The second bug is a rounding error in the reduced blanking calculation:
expand the ideal_duty_cylce to be in parts per ten thousand to avoid
rounding errors.
Signed-off-by: Martin Bugge <marbugge@cisco.com>
Cc: Mats Randgaard <matrandg@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
| -rw-r--r-- | drivers/media/v4l2-core/v4l2-dv-timings.c | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/drivers/media/v4l2-core/v4l2-dv-timings.c b/drivers/media/v4l2-core/v4l2-dv-timings.c index f20b316..72cf224 100644 --- a/drivers/media/v4l2-core/v4l2-dv-timings.c +++ b/drivers/media/v4l2-core/v4l2-dv-timings.c @@ -286,14 +286,14 @@ 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 + 999999) / 1000000; + v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 1999999) / 1000000; 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 + 999999) / 1000000 - vsync; + v_bp = (CVT_MIN_VSYNC_BP * hfreq + 1999999) / 1000000 - vsync; if (v_bp < CVT_MIN_V_BPORCH) v_bp = CVT_MIN_V_BPORCH; @@ -337,17 +337,16 @@ bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync, frame_width = image_width + CVT_RB_H_BLANK; } else { + unsigned ideal_duty_cycle_per_myriad = + 100 * CVT_C_PRIME - (CVT_M_PRIME * 100000) / hfreq; int h_blank; - unsigned ideal_duty_cycle = CVT_C_PRIME - (CVT_M_PRIME * 1000) / hfreq; - h_blank = (image_width * ideal_duty_cycle + (100 - ideal_duty_cycle) / 2) / - (100 - ideal_duty_cycle); - h_blank = h_blank - h_blank % (2 * CVT_CELL_GRAN); + if (ideal_duty_cycle_per_myriad < 2000) + ideal_duty_cycle_per_myriad = 2000; - if (h_blank * 100 / image_width < 20) { - h_blank = image_width / 5; - h_blank = (h_blank + 0x7) & ~0x7; - } + h_blank = image_width * ideal_duty_cycle_per_myriad / + (10000 - ideal_duty_cycle_per_myriad); + h_blank = (h_blank / (2 * CVT_CELL_GRAN)) * 2 * CVT_CELL_GRAN; pix_clk = (image_width + h_blank) * hfreq; pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN; |