Max,
On 7/5/24 9:54 AM, Max Staudt wrote:
> Hi Bingbu,
>
> Thanks for your review! Replies inline...
>
>
> On 7/4/24 4:03 PM, Bingbu Cao wrote:
>>> diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
>>> index 3ff390b04e1a..e7aee7e3db5b 100644
>>> --- a/drivers/staging/media/ipu3/ipu3-v4l2.c
>>> +++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
>>> @@ -535,29 +535,51 @@ static void imgu_vb2_stop_streaming(struct vb2_queue *vq)
>>> container_of(vq, struct imgu_video_device, vbq);
>>> int r;
>>> unsigned int pipe;
>>> + bool stop_streaming = false;
>>> + /* Verify that the node had been setup with imgu_v4l2_node_setup() */
>>> WARN_ON(!node->enabled);
>>> pipe = node->pipe;
>>> dev_dbg(dev, "Try to stream off node [%u][%u]", pipe, node->id);
>>> - imgu_pipe = &imgu->imgu_pipe[pipe];
>>> - r = v4l2_subdev_call(&imgu_pipe->imgu_sd.subdev, video, s_stream, 0);
>>> - if (r)
>>> - dev_err(&imgu->pci_dev->dev,
>>> - "failed to stop subdev streaming\n");
>>
>> I guess the subdev streams API can help us on this, but current fix
>> looks fine for me.
>
> I don't understand what you're referring to, since your comment is in relation to a block of existing code that I have merely shuffled around. Could you please elaborate?
I guess the real problem is the subdev s_stream cannot be called multiple
times, please correct me if I am wrong as I have not touch IPU3 for long
time. :)
You can ignore my previous comment - 's_stream' is fine here.
>
>
>>> + /*
>>> + * When the first node of a streaming setup is stopped, the entire
>>> + * pipeline needs to stop before individual nodes are disabled.
>>> + * Perform the inverse of the initial setup.
>>> + *
>>> + * Part 1 - s_stream on the entire pipeline
>>
>> stream on or off? it is a little confusing.
>
> I meant that s_stream(off) is called "on the entire pipeline".
>
> Thanks, I'll rephrase this in v2 :)
:)
>
>
>>> + */
>>> mutex_lock(&imgu->streaming_lock);
>>> - /* Was this the first node with streaming disabled? */
>>> if (imgu->streaming) {
>>> /* Yes, really stop streaming now */
>>> dev_dbg(dev, "IMGU streaming is ready to stop");
>>> r = imgu_s_stream(imgu, false);
>>> if (!r)
>>> imgu->streaming = false;
>>> + stop_streaming = true;
>>> }
>>> -
>>> mutex_unlock(&imgu->streaming_lock);
>>> + /* Part 2 - s_stream on subdevs
>>> + *
>>> + * If we call s_stream multiple times, Linux v6.7's call_s_stream()
>>> + * WARNs and aborts. Thus, disable all pipes at once, and only once.
>>> + */
>>> + if (stop_streaming) {
>>
>>> + for_each_set_bit(pipe, imgu->css.enabled_pipes,
>>> + IMGU_MAX_PIPE_NUM) {
>>> + imgu_pipe = &imgu->imgu_pipe[pipe];
>>> +
>>> + r = v4l2_subdev_call(&imgu_pipe->imgu_sd.subdev,
>>> + video, s_stream, 0);
>>> + if (r)
>>> + dev_err(&imgu->pci_dev->dev,
>>> + "failed to stop subdev streaming\n");
>>> + }
>>
>> Is it possible to move this loop into 'if (imgu->streaming)' above?
>
> The point of separating the loop from 'if (imgu->streaming)', and why the stop_streaming variable exists, is to keep the loop out of the mutex's hot path. This follows the code in imgu_vb2_start_streaming(), as mentioned in the commit message.
>
> Is it safe to do this work with the mutex taken?
>
> Is there any need to do this work with the mutex taken?
>
> Should the streamoff path really be different from the streamon path?
>
> Does this mean that the streamon path should also have this happen with the mutex taken?
Just a nit, stop_stream and s_stream only happen after imgu_s_stream(), so I
think they can be together and no need 'stop_streaming'. I think the mutex
is mainly for imgu_s_stream, subdev stream on/off should work without it.
It depends on you. :)
It'll be better that others who is still working on IPU3 devices can review.
Besides,
Reviewed-by: Bingbu Cao <bingbu.cao@xxxxxxxxx>
>
>
>
> Thanks,
>
> Max
>
>
--
Best regards,
Bingbu Cao
