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media: adv7842: enable reduced fps detection

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The pixelclock detection of the adv7842 is precise enough to detect
if the framerate is 60 Hz or 59.94 Hz (aka "reduced fps").

Implement this detection.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Hans Verkuil 2018-08-15 08:54:43 -04:00 committed by Mauro Carvalho Chehab
parent 3ae17c66ed
commit d842a7cf93
1 changed files with 9 additions and 0 deletions
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9
drivers/media/i2c/adv7842.c
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@ -1525,6 +1525,7 @@ static void adv7842_fill_optional_dv_timings_fields(struct v4l2_subdev *sd,
v4l2_find_dv_timings_cap(timings, adv7842_get_dv_timings_cap(sd),
is_digital_input(sd) ? 250000 : 1000000,
adv7842_check_dv_timings, NULL);
timings->bt.flags |= V4L2_DV_FL_CAN_DETECT_REDUCED_FPS;
}
static int adv7842_query_dv_timings(struct v4l2_subdev *sd,
@ -1596,6 +1597,14 @@ static int adv7842_query_dv_timings(struct v4l2_subdev *sd,
bt->il_vbackporch = 0;
}
adv7842_fill_optional_dv_timings_fields(sd, timings);
if ((timings->bt.flags & V4L2_DV_FL_CAN_REDUCE_FPS) &&
freq < bt->pixelclock) {
u32 reduced_freq = ((u32)bt->pixelclock / 1001) * 1000;
u32 delta_freq = abs(freq - reduced_freq);
if (delta_freq < ((u32)bt->pixelclock - reduced_freq) / 2)
timings->bt.flags |= V4L2_DV_FL_REDUCED_FPS;
}
} else {
/* find format
* Since LCVS values are inaccurate [REF_03, p. 339-340],