Hi Gabriel,
Thanks for your patch.
On 10/9/18 9:49 PM, Gabriel Francisco Mandaji wrote:
> Simulate a more precise timestamp by calculating it based on the
> current framerate.
>
> Signed-off-by: Gabriel Francisco Mandaji <gfmandaji@xxxxxxxxx>
> ---
> drivers/media/platform/vivid/vivid-core.h | 1 +
> drivers/media/platform/vivid/vivid-kthread-cap.c | 24 ++++++++++++++++--------
> 2 files changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/media/platform/vivid/vivid-core.h b/drivers/media/platform/vivid/vivid-core.h
> index cd4c823..cbdadd8 100644
> --- a/drivers/media/platform/vivid/vivid-core.h
> +++ b/drivers/media/platform/vivid/vivid-core.h
> @@ -384,6 +384,7 @@ struct vivid_dev {
> /* thread for generating video capture stream */
> struct task_struct *kthread_vid_cap;
> unsigned long jiffies_vid_cap;
> + u64 cap_stream_start;
> u32 cap_seq_offset;
> u32 cap_seq_count;
> bool cap_seq_resync;
> diff --git a/drivers/media/platform/vivid/vivid-kthread-cap.c b/drivers/media/platform/vivid/vivid-kthread-cap.c
> index f06003b..0793b15 100644
> --- a/drivers/media/platform/vivid/vivid-kthread-cap.c
> +++ b/drivers/media/platform/vivid/vivid-kthread-cap.c
> @@ -416,6 +416,7 @@ static void vivid_fillbuff(struct vivid_dev *dev, struct vivid_buffer *buf)
> char str[100];
> s32 gain;
> bool is_loop = false;
> + u64 soe_time = 0;
>
> if (dev->loop_video && dev->can_loop_video &&
> ((vivid_is_svid_cap(dev) &&
> @@ -426,11 +427,11 @@ static void vivid_fillbuff(struct vivid_dev *dev, struct vivid_buffer *buf)
>
> buf->vb.sequence = dev->vid_cap_seq_count;
> /*
> - * Take the timestamp now if the timestamp source is set to
> - * "Start of Exposure".
> + * Store the current time to calculate the delta if source is set to
> + * "End of Frame".
> */
> - if (dev->tstamp_src_is_soe)
> - buf->vb.vb2_buf.timestamp = ktime_get_ns();
> + if (!dev->tstamp_src_is_soe)
> + soe_time = ktime_get_ns();
> if (dev->field_cap == V4L2_FIELD_ALTERNATE) {
> /*
> * 60 Hz standards start with the bottom field, 50 Hz standards
> @@ -556,12 +557,18 @@ static void vivid_fillbuff(struct vivid_dev *dev, struct vivid_buffer *buf)
> }
>
> /*
> - * If "End of Frame" is specified at the timestamp source, then take
> - * the timestamp now.
> + * If "End of Frame", then calculate the "exposition time" and add
> + * it to the timestamp.
> */
> if (!dev->tstamp_src_is_soe)
> - buf->vb.vb2_buf.timestamp = ktime_get_ns();
> - buf->vb.vb2_buf.timestamp += dev->time_wrap_offset;
> + soe_time = ktime_get_ns() - soe_time;
If I understand correctly, soe_time here is the elapsed time (the delta
between the beginning of the frame and the end of it), so I thing naming
it etime or frame_time or delta_time would be clearer, because soe
stands for "start of exposure" and doesn't seem to be the right meaning.
> + buf->vb.vb2_buf.timestamp = dev->timeperframe_vid_cap.numerator *
> + 1000000000 /
> + dev->timeperframe_vid_cap.denominator *
> + dev->vid_cap_seq_count +
> + dev->cap_stream_start +
> + soe_time +
> + dev->time_wrap_offset;
Could you move the dev->vid_cap_seq_count to the top? I got confused if
it was multiplying only the denominator, I think moving to the top makes
it clearer (or add parenthesis).
> }
>
> /*
> @@ -759,6 +766,7 @@ static int vivid_thread_vid_cap(void *data)
> dev->cap_seq_count = 0;
> dev->cap_seq_resync = false;
> dev->jiffies_vid_cap = jiffies;
> + dev->cap_stream_start = ktime_get_ns();
>
> for (;;) {
> try_to_freeze();
>
Thanks
Helen
