Hi Prashant,
Sorry for the late review, but here it is (finally):
On 08/23/2015 04:09 PM, Prashant Laddha wrote:
> If bt timing has REDUCED_FPS flag set, then reduce the frame rate
> by factor of 1000 / 1001. For vivid, timeperframe_vid_out indicates
> the frame timings used by video out thread. The timeperframe_vid_out
> is derived from pixel clock. Adjusting the timeperframe_vid_out by
> scaling down pixel clock with factor of 1000 / 1001.
>
> The reduced fps is supported for CVT timings if reduced blanking v2
> (indicated by vsync = 8) is true. For CEA861 timings, reduced fps is
> supported if V4L2_DV_FL_CAN_REDUCE_FPS flag is true. For GTF timings,
> reduced fps is not supported.
>
> The reduced fps will allow refresh rates like 29.97, 59.94 etc.
>
> Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> Signed-off-by: Prashant Laddha <prladdha@xxxxxxxxx>
> ---
> drivers/media/platform/vivid/vivid-vid-out.c | 30 +++++++++++++++++++++++++++-
> drivers/media/v4l2-core/v4l2-dv-timings.c | 5 +++++
> 2 files changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/vivid/vivid-vid-out.c b/drivers/media/platform/vivid/vivid-vid-out.c
> index c404e27..ca6ec78 100644
> --- a/drivers/media/platform/vivid/vivid-vid-out.c
> +++ b/drivers/media/platform/vivid/vivid-vid-out.c
> @@ -213,6 +213,27 @@ const struct vb2_ops vivid_vid_out_qops = {
> };
>
> /*
> + * Called to check conditions for reduced fps. For CVT timings, reduced
> + * fps is allowed only with reduced blanking v2 (vsync == 8). For CEA861
> + * timings, reduced fps is allowed if V4L2_DV_FL_CAN_REDUCE_FPS flag is
> + * true.
> + */
> +static bool reduce_fps(struct v4l2_bt_timings *bt)
> +{
> + if (!(bt->flags & V4L2_DV_FL_REDUCED_FPS))
> + return false;
> +
> + if ((bt->standards & V4L2_DV_BT_STD_CVT) && (bt->vsync == 8))
I propose that you add a static inline helper function to v4l2-dv-timings.h
to test for reduced blanking v2. This condition is way too magical...
If you add such a helper, then you should check if there is existing code
that could switch to this helper.
> + return true;
Bad indentation (one tab too far to the right).
> +
> + if ((bt->standards & V4L2_DV_BT_STD_CEA861) &&
> + (bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS))
> + return true;
Ditto.
> +
> + return false;
> +}
> +
> +/*
> * Called whenever the format has to be reset which can occur when
> * changing outputs, standard, timings, etc.
> */
> @@ -220,6 +241,7 @@ void vivid_update_format_out(struct vivid_dev *dev)
> {
> struct v4l2_bt_timings *bt = &dev->dv_timings_out.bt;
> unsigned size, p;
> + u64 pixelclock;
>
> switch (dev->output_type[dev->output]) {
> case SVID:
> @@ -241,8 +263,14 @@ void vivid_update_format_out(struct vivid_dev *dev)
> dev->sink_rect.width = bt->width;
> dev->sink_rect.height = bt->height;
> size = V4L2_DV_BT_FRAME_WIDTH(bt) * V4L2_DV_BT_FRAME_HEIGHT(bt);
> +
> + if (reduce_fps(bt))
> + pixelclock = div_u64((bt->pixelclock * 1000), 1001);
No need for the parenthesis around bt->pixelclock * 1000.
> + else
> + pixelclock = bt->pixelclock;
> +
> dev->timeperframe_vid_out = (struct v4l2_fract) {
> - size / 100, (u32)bt->pixelclock / 100
> + size / 100, (u32)pixelclock / 100
> };
> if (bt->interlaced)
> dev->field_out = V4L2_FIELD_ALTERNATE;
> diff --git a/drivers/media/v4l2-core/v4l2-dv-timings.c b/drivers/media/v4l2-core/v4l2-dv-timings.c
> index 6a83d61..adc03bd 100644
> --- a/drivers/media/v4l2-core/v4l2-dv-timings.c
> +++ b/drivers/media/v4l2-core/v4l2-dv-timings.c
> @@ -210,7 +210,12 @@ bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
> fnc, fnc_handle) &&
> v4l2_match_dv_timings(t, v4l2_dv_timings_presets + i,
> pclock_delta)) {
> + u32 flags = t->bt.flags & V4L2_DV_FL_REDUCED_FPS;
> +
> *t = v4l2_dv_timings_presets[i];
> + if (t->bt.flags & V4L2_DV_FL_CAN_REDUCE_FPS)
> + t->bt.flags |= flags;
> +
This isn't quite right. This doesn't support V4L2_DV_BT_DMT_4096X2160P60_RB
which is a CVT format with reduced blanking v2 and so it should support reduced
fps.
In theory the 'if' above should check for both the V4L2_DV_FL_CAN_REDUCE_FPS and
for CVT RB v2 (using the helper function I've proposed). However, that would
cause weird behavior with the V4L2_DV_BT_DMT_4096X2160P59_94_RB timings since
these are already reduced fps.
I think the best approach is to add V4L2_DV_FL_CAN_REDUCE_FPS to the
V4L2_DV_BT_DMT_4096X2160P60_RB definition in v4l2-dv-timings.h.
That way the code above is unchanged, and it will work as expected with
V4L2_DV_BT_DMT_4096X2160P60_RB.
Regards,
Hans
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