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SubjectRe: [PATCH v2 02/10] media-request: Add a request complete operation to allow m2m scheduling
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On 04/19/18 17:41, Paul Kocialkowski wrote:
> When using the request API in the context of a m2m driver, the
> operations that come with a m2m run scheduling call in their
> (m2m-specific) ioctl handler are delayed until the request is queued
> (for instance, this includes queuing buffers and streamon).
>
> Thus, the m2m run scheduling calls are not called in due time since the
> request AP's internal plumbing will (rightfully) use the relevant core
> functions directly instead of the ioctl handler.
>
> This ends up in a situation where nothing happens if there is no
> run-scheduling ioctl called after queuing the request.
>
> In order to circumvent the issue, a new media operation is introduced,
> called at the time of handling the media request queue ioctl. It gives
> m2m drivers a chance to schedule a m2m device run at that time.
>
> The existing req_queue operation cannot be used for this purpose, since
> it is called with the request queue mutex held, that is eventually needed
> in the device_run call to apply relevant controls.

I'll need to think about this a bit more. I understand the problem so something
needs to be done. I would like to avoid adding yet another op, though.

Regards,

Hans

>
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> ---
> drivers/media/media-request.c | 3 +++
> include/media/media-device.h | 2 ++
> 2 files changed, 5 insertions(+)
>
> diff --git a/drivers/media/media-request.c b/drivers/media/media-request.c
> index 415f7e31019d..28ac5ccfe6a2 100644
> --- a/drivers/media/media-request.c
> +++ b/drivers/media/media-request.c
> @@ -157,6 +157,9 @@ static long media_request_ioctl_queue(struct media_request *req)
> media_request_get(req);
> }
>
> + if (mdev->ops->req_complete)
> + mdev->ops->req_complete(req);
> +
> return ret;
> }
>
> diff --git a/include/media/media-device.h b/include/media/media-device.h
> index 07e323c57202..c7dcf2079cc9 100644
> --- a/include/media/media-device.h
> +++ b/include/media/media-device.h
> @@ -55,6 +55,7 @@ struct media_entity_notify {
> * @req_alloc: Allocate a request
> * @req_free: Free a request
> * @req_queue: Queue a request
> + * @req_complete: Complete a request
> */
> struct media_device_ops {
> int (*link_notify)(struct media_link *link, u32 flags,
> @@ -62,6 +63,7 @@ struct media_device_ops {
> struct media_request *(*req_alloc)(struct media_device *mdev);
> void (*req_free)(struct media_request *req);
> int (*req_queue)(struct media_request *req);
> + void (*req_complete)(struct media_request *req);
> };
>
> /**
>

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