linux-kernel - Re: [PATCH v3 3/9] media: venus: adding core part and helper functions

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Date:   Mon, 14 Nov 2016 12:11:51 +0200
From:   Stanimir Varbanov <stanimir.varbanov@...aro.org>
To:     Hans Verkuil <hverkuil@...all.nl>,
        Stanimir Varbanov <stanimir.varbanov@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v3 3/9] media: venus: adding core part and helper
 functions

Hi Hans,

<cut>

>>>
>>>> +void vidc_vb2_stop_streaming(struct vb2_queue *q)
>>>> +{
>>>> +	struct venus_inst *inst = vb2_get_drv_priv(q);
>>>> +	struct venus_core *core = inst->core;
>>>> +	struct device *dev = core->dev;
>>>> +	struct vb2_queue *other_queue;
>>>> +	struct vidc_buffer *buf, *n;
>>>> +	enum vb2_buffer_state state;
>>>> +	int ret;
>>>> +
>>>> +	if (q->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
>>>> +		other_queue = &inst->bufq_cap;
>>>> +	else
>>>> +		other_queue = &inst->bufq_out;
>>>> +
>>>> +	if (!vb2_is_streaming(other_queue))
>>>> +		return;
>>>
>>> This seems wrong to me: this return means that the buffers of queue q are never
>>> released. Either drop this 'if' or release both queues when the last queue
>>> stops streaming. I think dropping the 'if' is best.
>>
>> I have done this way because hfi_session_stop must be called only once,
>> and buffers will be released on first streamoff for both queues.
> 
> Are you sure the buffers are released for both queues? I may have missed that when
> reviewing.

yes, hfi_session_stop will instruct the firmware to stop using provided
buffers and return ownership to the host driver by fill_buf_done and
empty_buf_done callbacks.

> 
> I would recommend to call hfi_session_stop when the first stop_streaming is called,
> not when it is called for both queues. I say this because stopping streaming without
> releasing the buffers is likely to cause problems.

this is what I tried to implement with above
!vb2_is_streaming(other_queue) thing.

> 
> Did you turn on CONFIG_VIDEO_ADV_DEBUG? If it is on, and you don't release buffers
> then I think you will see warnings in the kernel log.

OK I will enable it to be sure that warnings are missing.

-- 
regards,
Stan