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

[Dafna Hirschfeld <dafna.hirschfeld@collabora.com>]

Hi

Am 17.08.20 um 23:48 schrieb Helen Koike:
> 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././

Actually the debugfs counter for dropped frames is incremented
when there is a frame ready on the capture but there are no buffers in the v4l2 queue.
It is quit unrelated to the v-start event, so I think the whole comment can be dropped.

Thanks,
Dafna

> 
> 
> 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 */
>>

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