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

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Message-ID: <72f8675a-4771-3e9a-6ee0-6e1b86589e8f@xs4all.nl>
Date:   Mon, 14 Nov 2016 11:25:36 +0100
From:   Hans Verkuil <hverkuil@...all.nl>
To:     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

On 11/14/2016 11:11 AM, Stanimir Varbanov wrote:
> 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.

That doesn't work: if the application calls STREAMON(CAPTURE) followed by STREAMOFF(CAPTURE)
without ever starting the OUTPUT queue, this will not clean up the capture queue.

Regards,

	Hans

> 
>>
>> 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.
>