From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
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@xxxxxxxxx>
---
drivers/media/i2c/adv7842.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/media/i2c/adv7842.c b/drivers/media/i2c/adv7842.c
index 4f8fbdd00e35..999d621f5667 100644
--- a/drivers/media/i2c/adv7842.c
+++ b/drivers/media/i2c/adv7842.c
@@ -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 = (bt->pixelclock / 1001) * 1000;
+ u32 delta_freq = abs(freq - reduced_freq);
+
+ if (delta_freq < (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],
--
2.18.0
