Hi Sakari,
Thank you for the patch.
On Friday, 8 September 2017 16:11:53 EEST Sakari Ailus wrote:
> Remove V4L2 async re-probing support. The re-probing support has been
> there to support cases where the sub-devices require resources provided by
> the main driver's hardware to function, such as clocks.
>
> Reprobing has allowed unbinding and again binding the main driver without
> explicilty unbinding the sub-device drivers. This is certainly not a
> common need, and the responsibility will be the user's going forward.
>
> An alternative could have been to introduce notifier specific locks.
> Considering the complexity of the re-probing and that it isn't really a
> solution to a problem but a workaround, remove re-probing instead.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
I agree that this is a hack, and that the problem should be addressed
differently. I'm fine with this patch as it helps later rework of the async
notifier code, but we need a plan to fix the problem.
> ---
> drivers/media/v4l2-core/v4l2-async.c | 54 ---------------------------------
> 1 file changed, 54 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-async.c
> b/drivers/media/v4l2-core/v4l2-async.c index d741a8e0fdac..e109d9da4653
> 100644
> --- a/drivers/media/v4l2-core/v4l2-async.c
> +++ b/drivers/media/v4l2-core/v4l2-async.c
> @@ -198,78 +198,24 @@ EXPORT_SYMBOL(v4l2_async_notifier_register);
> void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> {
> struct v4l2_subdev *sd, *tmp;
> - unsigned int notif_n_subdev = notifier->num_subdevs;
> - unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
> - struct device **dev;
> - int i = 0;
>
> if (!notifier->v4l2_dev)
> return;
>
> - dev = kvmalloc_array(n_subdev, sizeof(*dev), GFP_KERNEL);
> - if (!dev) {
> - dev_err(notifier->v4l2_dev->dev,
> - "Failed to allocate device cache!\n");
> - }
> -
> mutex_lock(&list_lock);
>
> list_del(¬ifier->list);
>
> list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) {
> - struct device *d;
> -
> - d = get_device(sd->dev);
> -
> v4l2_async_cleanup(sd);
>
> - /* If we handled USB devices, we'd have to lock the parent too */
> - device_release_driver(d);
> -
> if (notifier->unbind)
> notifier->unbind(notifier, sd, sd->asd);
> -
> - /*
> - * Store device at the device cache, in order to call
> - * put_device() on the final step
> - */
> - if (dev)
> - dev[i++] = d;
> - else
> - put_device(d);
> }
>
> mutex_unlock(&list_lock);
>
> - /*
> - * Call device_attach() to reprobe devices
> - *
> - * NOTE: If dev allocation fails, i is 0, and the whole loop won't be
> - * executed.
> - */
> - while (i--) {
> - struct device *d = dev[i];
> -
> - if (d && device_attach(d) < 0) {
> - const char *name = "(none)";
> - int lock = device_trylock(d);
> -
> - if (lock && d->driver)
> - name = d->driver->name;
> - dev_err(d, "Failed to re-probe to %s\n", name);
> - if (lock)
> - device_unlock(d);
> - }
> - put_device(d);
> - }
> - kvfree(dev);
> -
> notifier->v4l2_dev = NULL;
> -
> - /*
> - * Don't care about the waiting list, it is initialised and populated
> - * upon notifier registration.
> - */
> }
> EXPORT_SYMBOL(v4l2_async_notifier_unregister);
--
Regards,
Laurent Pinchart
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