Re: [PATCH] ALSA: pcm: Show closed for DISCONNECTED state

[Jaroslav Kysela]

On 6/17/26 09:19, Ai Chao wrote:
> Hello Takashi
>
> > Thanks, it's a bit clearer.  But it still means that it's a cargo fix
> > only for that specific application.  The program should receive an
> > error for any further syscalls, so that it can close gracefully by
> > itself.  Or it doesn't work as expected?
>
> The recording software monitors /proc/asound/card0/pcm0c/sub0/status.
> When the USB device is suddenly disconnected, the recording software fails
> to capture audio data from the sound card, with both the hardware pointer
> and application pointer being 0. The software remains in a pending state,
> continuously displaying "Generating recording file". If the status file shows
> "closed" (DISCONNECTED), the audio service detects the status change, reinitializes
> the device, starts processing the recording file, and either resumes recording or
> notifies the user.

The PCM API ioctls should return an error in this case (device disconnection). 
Does software communicate with the driver through ioctl ? It seems that only 
mmaped appl/hw pointers are used which is not enough to detect the disconnection.

Obtaining the device state through procfs is really a bad habit.

					Jaroslav

--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.