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

From: Hans Verkuil
Date: Mon Nov 14 2016 - 05:26:52 EST


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.
>