On Wed, 03 Feb 2021 18:34:12 +0100, Anton Yakovlev wrote:
Hi Takashi,
On 03.02.2021 17:59, Takashi Iwai wrote:
On Tue, 02 Feb 2021 00:18:09 +0100, Anton Yakovlev wrote:
+/**
- virtsnd_reset_fn() - Kernel worker's function to reset the device.
- @work: Reset device work.
- Context: Process context.
- */
+static void virtsnd_reset_fn(struct work_struct *work) +{
struct virtio_snd *snd =container_of(work, struct virtio_snd, reset_work);struct virtio_device *vdev = snd->vdev;struct device *dev = &vdev->dev;int rc;dev_info(dev, "sound device needs reset\n");/** It seems that the only way to properly reset the device is toremove
* and re-create the ALSA sound card device.** Also resetting the device involves a number of steps withsetting the
* status bits described in the virtio specification. And theeasiest
* way to get everything right is to use the virtio bus interface.*/rc = dev->bus->remove(dev);if (rc)dev_warn(dev, "bus->remove() failed: %d", rc);rc = dev->bus->probe(dev);if (rc)dev_err(dev, "bus->probe() failed: %d", rc);This looks very suspicious to me. Wondering what ALSA maintainers
will say
to this.
I'm also wondering what the virtio people have to say. This part is a purely virtio specific thing. And since none of the existing virtio drivers processes the request to reset the device, it is not clear what is the best way to proceed here. For this reason, the most straightforward and simple solution was chosen.
What is this "reset" actually supposed to do? Reconfguring everything, or changing only certain parameters, devices, whatever?
It means bringing this particular device to its initial state.
After that, the driver can re-read the configurations from the device and reconfigure everything.
So all running processes have to be finished before starting resetting? It sounds indeed like a complete device re-binding, and if so, doing with the proper dev_*() API might be saner than the brute force bus->remove() and bus->probe() calls...
thanks,
Takashi