Re: [PATCH v2 09/14] media: staging: rkisp1: remove atomic operations for frame sequence

[Helen Koike <helen.koike@collabora.com>]

Hi Dafna,

On 8/15/20 7:37 AM, Dafna Hirschfeld wrote:
> The isp.frame_sequence is now read only from the irq handlers
> that are all fired from the same interrupt so there is not need
> for atomic operation.
> In addition the frame seq incrementation is moved from
> rkisp1_isp_queue_event_sof to rkisp1_isp_isr to make the code
> clearer.
> 
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
> ---
>  drivers/staging/media/rkisp1/rkisp1-capture.c |  2 +-
>  drivers/staging/media/rkisp1/rkisp1-common.h  |  2 +-
>  drivers/staging/media/rkisp1/rkisp1-isp.c     | 20 +++++++++----------
>  drivers/staging/media/rkisp1/rkisp1-params.c  |  2 +-
>  drivers/staging/media/rkisp1/rkisp1-stats.c   |  3 +--
>  5 files changed, 14 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/staging/media/rkisp1/rkisp1-capture.c b/drivers/staging/media/rkisp1/rkisp1-capture.c
> index c05280950ea0..d7017afc5405 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-capture.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-capture.c
> @@ -632,7 +632,7 @@ static void rkisp1_handle_buffer(struct rkisp1_capture *cap)
>  	curr_buf = cap->buf.curr;
>  
>  	if (curr_buf) {
> -		curr_buf->vb.sequence = atomic_read(&isp->frame_sequence);
> +		curr_buf->vb.sequence = isp->frame_sequence;
>  		curr_buf->vb.vb2_buf.timestamp = ktime_get_boottime_ns();
>  		curr_buf->vb.field = V4L2_FIELD_NONE;
>  		vb2_buffer_done(&curr_buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> diff --git a/drivers/staging/media/rkisp1/rkisp1-common.h b/drivers/staging/media/rkisp1/rkisp1-common.h
> index 9b41935c6597..79edece6ee77 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-common.h
> +++ b/drivers/staging/media/rkisp1/rkisp1-common.h
> @@ -112,7 +112,7 @@ struct rkisp1_isp {
>  	const struct rkisp1_isp_mbus_info *src_fmt;
>  	struct mutex ops_lock;
>  	bool is_dphy_errctrl_disabled;
> -	atomic_t frame_sequence;
> +	__u32 frame_sequence;
>  };
>  
>  struct rkisp1_vdev_node {
> diff --git a/drivers/staging/media/rkisp1/rkisp1-isp.c b/drivers/staging/media/rkisp1/rkisp1-isp.c
> index ad2ece78abbf..1ffe7cc7bb12 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-isp.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-isp.c
> @@ -940,7 +940,7 @@ static int rkisp1_isp_s_stream(struct v4l2_subdev *sd, int enable)
>  	if (rkisp1->active_sensor->mbus_type != V4L2_MBUS_CSI2_DPHY)
>  		return -EINVAL;
>  
> -	atomic_set(&rkisp1->isp.frame_sequence, -1);
> +	rkisp1->isp.frame_sequence = -1;
>  	mutex_lock(&isp->ops_lock);
>  	ret = rkisp1_config_cif(rkisp1);
>  	if (ret)
> @@ -1093,15 +1093,8 @@ static void rkisp1_isp_queue_event_sof(struct rkisp1_isp *isp)
>  	struct v4l2_event event = {
>  		.type = V4L2_EVENT_FRAME_SYNC,
>  	};
> +	event.u.frame_sync.frame_sequence = isp->frame_sequence;
>  
> -	/*
> -	 * Increment the frame sequence on the vsync signal.
> -	 * This will allow applications to detect dropped.
> -	 * Note that there is a debugfs counter for dropped
> -	 * frames, but using this event is more accurate.
> -	 */
> -	event.u.frame_sync.frame_sequence =
> -		atomic_inc_return(&isp->frame_sequence);
>  	v4l2_event_queue(isp->sd.devnode, &event);
>  }
>  
> @@ -1116,7 +1109,14 @@ void rkisp1_isp_isr(struct rkisp1_device *rkisp1)
>  	rkisp1_write(rkisp1, status, RKISP1_CIF_ISP_ICR);
>  
>  	/* Vertical sync signal, starting generating new frame */
> -	if (status & RKISP1_CIF_ISP_V_START)
> +	if (status & RKISP1_CIF_ISP_V_START) {
> +		/*
> +		 * Increment the frame sequence on the vsync signal.
> +		 * This will allow applications to detect dropped.

I know just moved the comment, but I would like to take this opportunity
to fix this text:

s/to detect dropped/to detect dropped frames.

> +		 * Note that there is a debugfs counter for dropped
> +		 * frames, but using this event is more accurate.

I'm not sure if this phrase is accurate :P
Since the debugfs counter should be reliable to verify we dropped frames.

I mean, usage is different.

maybe just:

s/, but using this event is more accurate././


With or without these changes:

Acked-by: Helen Koike <helen.koike@collabora.com>

Regards,
Helen

> +		 */
> +		rkisp1->isp.frame_sequence++;
>  		rkisp1_isp_queue_event_sof(&rkisp1->isp);
>  
>  	if (status & RKISP1_CIF_ISP_PIC_SIZE_ERROR) {
> diff --git a/drivers/staging/media/rkisp1/rkisp1-params.c b/drivers/staging/media/rkisp1/rkisp1-params.c
> index 4b4391c0a2a0..cc242ad5106e 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-params.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-params.c
> @@ -1227,7 +1227,7 @@ void rkisp1_params_isr(struct rkisp1_device *rkisp1)
>  	 * We want the vb.sequence to be the frame that the params are applied to.
>  	 * So we set vb.sequence to be the isp's frame_sequence + 1
>  	 */
> -	unsigned int frame_sequence = atomic_read(&rkisp1->isp.frame_sequence) + 1;
> +	unsigned int frame_sequence = rkisp1->isp.frame_sequence + 1;
>  	struct rkisp1_params *params = &rkisp1->params;
>  
>  	spin_lock(&params->config_lock);
> diff --git a/drivers/staging/media/rkisp1/rkisp1-stats.c b/drivers/staging/media/rkisp1/rkisp1-stats.c
> index 87e4104d20dd..52417b388854 100644
> --- a/drivers/staging/media/rkisp1/rkisp1-stats.c
> +++ b/drivers/staging/media/rkisp1/rkisp1-stats.c
> @@ -307,8 +307,7 @@ rkisp1_stats_send_measurement(struct rkisp1_stats *stats, u32 isp_ris)
>  {
>  	struct rkisp1_stat_buffer *cur_stat_buf;
>  	struct rkisp1_buffer *cur_buf = NULL;
> -	unsigned int frame_sequence =
> -		atomic_read(&stats->rkisp1->isp.frame_sequence);
> +	unsigned int frame_sequence = stats->rkisp1->isp.frame_sequence;
>  	u64 timestamp = ktime_get_ns();
>  
>  	/* get one empty buffer */
>