Re: [PATCH v2 01/23] media: iris: Skip destroying internal buffer if not dequeued

[Dikshita Agarwal <quic_dikshita@quicinc.com>]

On 4/29/2025 6:17 PM, Nicolas Dufresne wrote:
> Not mine to review, but wanted to highlight some best practices,
> 
> comment below...
> 
> Le lundi 28 avril 2025 à 14:58 +0530, Dikshita Agarwal a écrit :
>> Firmware might hold the DPB buffers for reference in case of sequence
>> change, so skip destroying buffers for which QUEUED flag is not removed.
>> Also, make sure that all buffers are released during streamoff.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 73702f45db81 ("media: iris: allocate, initialize and queue internal buffers")
>> Signed-off-by: Dikshita Agarwal <quic_dikshita@quicinc.com>
>> ---
>>  drivers/media/platform/qcom/iris/iris_buffer.c | 37 +++++++++++++++++++++++++-
>>  drivers/media/platform/qcom/iris/iris_buffer.h |  3 ++-
>>  drivers/media/platform/qcom/iris/iris_vdec.c   |  4 +--
>>  drivers/media/platform/qcom/iris/iris_vidc.c   |  6 +++--
>>  4 files changed, 44 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/media/platform/qcom/iris/iris_buffer.c b/drivers/media/platform/qcom/iris/iris_buffer.c
>> index e5c5a564fcb8..606d76b10be2 100644
>> --- a/drivers/media/platform/qcom/iris/iris_buffer.c
>> +++ b/drivers/media/platform/qcom/iris/iris_buffer.c
>> @@ -376,7 +376,7 @@ int iris_destroy_internal_buffer(struct iris_inst *inst, struct iris_buffer *buf
>>  	return 0;
>>  }
>>  
>> -int iris_destroy_internal_buffers(struct iris_inst *inst, u32 plane)
>> +int iris_destroy_internal_buffers(struct iris_inst *inst, u32 plane, bool force)
> 
> Its always tempting to just glue a boolean at the end of a parameter
> list. But this has huge downside in code readability, see below...
> 
>>  {
>>  	const struct iris_platform_data *platform_data = inst->core->iris_platform_data;
>>  	struct iris_buffer *buf, *next;
>> @@ -396,6 +396,14 @@ int iris_destroy_internal_buffers(struct iris_inst *inst, u32 plane)
>>  	for (i = 0; i < len; i++) {
>>  		buffers = &inst->buffers[internal_buf_type[i]];
>>  		list_for_each_entry_safe(buf, next, &buffers->list, list) {
>> +			/*
>> +			 * during stream on, skip destroying internal(DPB) buffer
>> +			 * if firmware did not return it.
>> +			 * during close, destroy all buffers irrespectively.
>> +			 */
>> +			if (!force && buf->attr & BUF_ATTR_QUEUED)
>> +				continue;
>> +
>>  			ret = iris_destroy_internal_buffer(inst, buf);
>>  			if (ret)
>>  				return ret;
>> @@ -446,6 +454,33 @@ static int iris_release_input_internal_buffers(struct iris_inst *inst)
>>  	return 0;
>>  }
>>  
>> +void iris_get_num_queued_internal_buffers(struct iris_inst *inst, u32 plane)
>> +{
>> +	const struct iris_platform_data *platform_data = inst->core->iris_platform_data;
>> +	struct iris_buffer *buf, *next;
>> +	struct iris_buffers *buffers;
>> +	const u32 *internal_buf_type;
>> +	u32 internal_buffer_count, i;
>> +	u32 count = 0;
>> +
>> +	if (V4L2_TYPE_IS_OUTPUT(plane)) {
>> +		internal_buf_type = platform_data->dec_ip_int_buf_tbl;
>> +		internal_buffer_count = platform_data->dec_ip_int_buf_tbl_size;
>> +	} else {
>> +		internal_buf_type = platform_data->dec_op_int_buf_tbl;
>> +		internal_buffer_count = platform_data->dec_op_int_buf_tbl_size;
>> +	}
>> +
>> +	for (i = 0; i < internal_buffer_count; i++) {
>> +		buffers = &inst->buffers[internal_buf_type[i]];
>> +		list_for_each_entry_safe(buf, next, &buffers->list, list)
>> +			count++;
>> +		if (count)
>> +			dev_err(inst->core->dev, "%d buffer of type %d not released",
>> +				count, internal_buf_type[i]);
>> +	}
>> +}
>> +
>>  int iris_alloc_and_queue_persist_bufs(struct iris_inst *inst)
>>  {
>>  	struct iris_buffers *buffers = &inst->buffers[BUF_PERSIST];
>> diff --git a/drivers/media/platform/qcom/iris/iris_buffer.h b/drivers/media/platform/qcom/iris/iris_buffer.h
>> index c36b6347b077..03a32b91cf21 100644
>> --- a/drivers/media/platform/qcom/iris/iris_buffer.h
>> +++ b/drivers/media/platform/qcom/iris/iris_buffer.h
>> @@ -106,7 +106,8 @@ void iris_get_internal_buffers(struct iris_inst *inst, u32 plane);
>>  int iris_create_internal_buffers(struct iris_inst *inst, u32 plane);
>>  int iris_queue_internal_buffers(struct iris_inst *inst, u32 plane);
>>  int iris_destroy_internal_buffer(struct iris_inst *inst, struct iris_buffer *buffer);
>> -int iris_destroy_internal_buffers(struct iris_inst *inst, u32 plane);
>> +int iris_destroy_internal_buffers(struct iris_inst *inst, u32 plane, bool force);
>> +void iris_get_num_queued_internal_buffers(struct iris_inst *inst, u32 plane);
>>  int iris_alloc_and_queue_persist_bufs(struct iris_inst *inst);
>>  int iris_alloc_and_queue_input_int_bufs(struct iris_inst *inst);
>>  int iris_queue_buffer(struct iris_inst *inst, struct iris_buffer *buf);
>> diff --git a/drivers/media/platform/qcom/iris/iris_vdec.c b/drivers/media/platform/qcom/iris/iris_vdec.c
>> index 4143acedfc57..2c1a7162d2da 100644
>> --- a/drivers/media/platform/qcom/iris/iris_vdec.c
>> +++ b/drivers/media/platform/qcom/iris/iris_vdec.c
>> @@ -408,7 +408,7 @@ int iris_vdec_streamon_input(struct iris_inst *inst)
>>  
>>  	iris_get_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);
>>  
>> -	ret = iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);
>> +	ret = iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE, false);
>>  	if (ret)
>>  		return ret;
>>  
>> @@ -496,7 +496,7 @@ int iris_vdec_streamon_output(struct iris_inst *inst)
>>  
>>  	iris_get_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
>>  
>> -	ret = iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
>> +	ret = iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE, false);
> 
> If I was reviewing some changes (or even debugging) this specific C
> file, I would not be able to understanding what this "false" means. I
> would have to spend extra time, opening the declaration, going back and
> forth, and breaking the flow.
> 
> An alternative approach is to keep the boolean parameter in a static
> function (c local), and then add two function wrappers that have
> explicit names.
> 
Sure, I can implement the alternative approach, if recommended.

If I understand correctly, you are suggesting to have one static helper and
two wrappers around this. like:

static int iris_destroy_internal_buffers(struct iris_inst *inst, u32 plane,
bool force)
{
	...
	list_for_each_entry_safe(buf, next, &buffers->list, list) {
       		if (!force && buf->attr & BUF_ATTR_QUEUED)
			continue;
		...
	}
	...
}

//called during stream on
int iris_destroy_dequeued_internal_buffers(struct iris_inst *inst, u32 plane)
{
	return iris_destroy_internal_buffers(inst, plane, false)
}

//called during close
int iris_destroy_all_internal_buffers(struct iris_inst *inst, u32 plane)
{
	return iris_destroy_internal_buffers(inst, plane, true)
}

Thanks,
Dikshita
> regards,
> Nicolas
> 
>>  	if (ret)
>>  		return ret;
>>  
>> diff --git a/drivers/media/platform/qcom/iris/iris_vidc.c b/drivers/media/platform/qcom/iris/iris_vidc.c
>> index ca0f4e310f77..56531a7f0dfe 100644
>> --- a/drivers/media/platform/qcom/iris/iris_vidc.c
>> +++ b/drivers/media/platform/qcom/iris/iris_vidc.c
>> @@ -233,8 +233,10 @@ int iris_close(struct file *filp)
>>  	iris_session_close(inst);
>>  	iris_inst_change_state(inst, IRIS_INST_DEINIT);
>>  	iris_v4l2_fh_deinit(inst);
>> -	iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);
>> -	iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
>> +	iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE, true);
>> +	iris_destroy_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE, true);
>> +	iris_get_num_queued_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);
>> +	iris_get_num_queued_internal_buffers(inst, V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);
>>  	iris_remove_session(inst);
>>  	mutex_unlock(&inst->lock);
>>  	mutex_destroy(&inst->ctx_q_lock);
>