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

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

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.

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);

-- 
Nicolas Dufresne
Principal Engineer at Collabora