Re: [PATCH v5 02/12] media: uvcvideo: Allow more that one asyc_ctrl

Laurent Pinchart
2020-12-22T08:08:45Z

Hi Ricardo,

Thank you for the patch.

On Mon, Dec 21, 2020 at 05:48:09PM +0100, Ricardo Ribalda wrote:
> The current implementation allocates memory for only one async_control.
> If we get a second event before we have processed the previous one, the
> old one gets lost.
>
> Introduce a dynamic memory allocation and a list to handle the
> async_controls.

Thinking some more about this, do we need to go through the work queue
at all for GPIO-based events ? Could the part of
uvc_ctrl_status_event_work() before the URB resubmission be moved to
another function, which would be called directly by the GPIO threaded
IRQ handler ?

> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 49 ++++++++++++++++++++++++++------
> drivers/media/usb/uvc/uvcvideo.h | 19 ++++++++-----
> 2 files changed, 52 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> index aa18dcdf8165..69b2fc6ce12c 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1275,11 +1275,9 @@ static void uvc_ctrl_send_slave_event(struct uvc_video_chain *chain,
> uvc_ctrl_send_event(chain, handle, ctrl, mapping, val, changes);
> }
>
> -static void uvc_ctrl_status_event_work(struct work_struct *work)
> +static void __uvc_ctrl_status_event_work(struct uvc_device *dev,
> + struct uvc_ctrl_work *w)
> {
> - struct uvc_device *dev = container_of(work, struct uvc_device,
> - async_ctrl.work);
> - struct uvc_ctrl_work *w = &dev->async_ctrl;
> struct uvc_video_chain *chain = w->chain;
> struct uvc_control_mapping *mapping;
> struct uvc_control *ctrl = w->ctrl;
> @@ -1321,23 +1319,54 @@ static void uvc_ctrl_status_event_work(struct work_struct *work)
> ret);
> }
>
> +static void uvc_ctrl_status_event_work(struct work_struct *work)
> +{
> + struct uvc_device *dev = container_of(work, struct uvc_device,
> + async_ctrl_work);
> + struct uvc_ctrl_work *w;
> +
> + do {
> + mutex_lock(&dev->async_ctrl_lock);
> + w = list_first_entry_or_null(&dev->async_ctrl_list,
> + struct uvc_ctrl_work,
> + list);
> + if (w)
> + list_del(&w->list);
> + mutex_unlock(&dev->async_ctrl_lock);
> +
> + if (!w)
> + return;
> +
> + __uvc_ctrl_status_event_work(dev, w);
> + kfree(w);
> + } while (w);
> +}
> +
> bool uvc_ctrl_status_event(struct urb *urb, struct uvc_video_chain *chain,
> struct uvc_control *ctrl, const u8 *data)
> {
> struct uvc_device *dev = chain->dev;
> - struct uvc_ctrl_work *w = &dev->async_ctrl;
> + struct uvc_ctrl_work *w;
>
> if (list_empty(&ctrl->info.mappings)) {
> ctrl->handle = NULL;
> return false;
> }
>
> + w = kzalloc(sizeof(*w), GFP_KERNEL);
> + if (WARN(!w, "Not enough memory to trigger uvc event"))
> + return false;
> +
> memcpy(w->data, data, ctrl->info.size);
> w->urb = urb;
> w->chain = chain;
> w->ctrl = ctrl;
>
> - schedule_work(&w->work);
> + mutex_lock(&dev->async_ctrl_lock);
> + list_add_tail(&w->list, &dev->async_ctrl_list);
> + mutex_unlock(&dev->async_ctrl_lock);
> +
> + schedule_work(&dev->async_ctrl_work);
>
> return true;
> }
> @@ -2277,7 +2306,9 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
> struct uvc_entity *entity;
> unsigned int i;
>
> - INIT_WORK(&dev->async_ctrl.work, uvc_ctrl_status_event_work);
> + INIT_WORK(&dev->async_ctrl_work, uvc_ctrl_status_event_work);
> + mutex_init(&dev->async_ctrl_lock);
> + INIT_LIST_HEAD(&dev->async_ctrl_list);
>
> /* Walk the entities list and instantiate controls */
> list_for_each_entry(entity, &dev->entities, list) {
> @@ -2348,8 +2379,8 @@ void uvc_ctrl_cleanup_device(struct uvc_device *dev)
> unsigned int i;
>
> /* Can be uninitialized if we are aborting on probe error. */
> - if (dev->async_ctrl.work.func)
> - cancel_work_sync(&dev->async_ctrl.work);
> + if (dev->async_ctrl_work.func)
> + cancel_work_sync(&dev->async_ctrl_work);
>
> /* Free controls and control mappings for all entities. */
> list_for_each_entry(entity, &dev->entities, list) {
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 0db6c2e0bd98..afcaf49fad1a 100644
> --- a/drivers/media/usb/uvc/uvcvideo.h
> +++ b/drivers/media/usb/uvc/uvcvideo.h
> @@ -637,6 +637,14 @@ struct uvc_device_info {
> u32 meta_format;
> };
>
> +struct uvc_ctrl_work {
> + struct list_head list;
> + struct urb *urb;
> + struct uvc_video_chain *chain;
> + struct uvc_control *ctrl;
> + u8 data[UVC_MAX_STATUS_SIZE];
> +};
> +
> struct uvc_device {
> struct usb_device *udev;
> struct usb_interface *intf;
> @@ -673,13 +681,10 @@ struct uvc_device {
> struct input_dev *input;
> char input_phys[64];
>
> - struct uvc_ctrl_work {
> - struct work_struct work;
> - struct urb *urb;
> - struct uvc_video_chain *chain;
> - struct uvc_control *ctrl;
> - u8 data[UVC_MAX_STATUS_SIZE];
> - } async_ctrl;
> + /* Async control */
> + struct work_struct async_ctrl_work;
> + struct list_head async_ctrl_list;
> + struct mutex async_ctrl_lock;
> };
>
> enum uvc_handle_state {

--
Regards,

Laurent Pinchart