On Mon, 18 Jan 2016 07:04:03 +0100, Kuninori Morimoto wrote: > > Hi Sakamoto-san > > Thank you for your feedback > > > > Our sound device needs recovery if under/over run error happen. > > > Basically, this "recovery" means "restart hardware". > > > But, in such case, who should recovers sound device, Kernel or Userland ? > > > > > > Current our sound driver recovers it by kernel automatically. > > > (But I need do work more for it) > > > > I think you should not recover it in kernel space, because 'hw_ptr' in > > mapped page includes values unexpected by userspace application. (The > > value may suddenly jump up to unexpected value after recovered.) > > > > What driver in kernel land is to notify XRUN to the applications in > > your case. If recovering processing includes event waiting, it should > > not be executed in interrupt context. > > > > > We considered that userland should know it, or, run it by himself (?) > > > If userland should do it, which function should be called to announce > > > error to userland from kernel ? > > > > Userspace can get to know the XRUN state by calling some APIs. Then, > > it can recover PCM substream by executing SNDRV_PCM_IOCTL_PREPARE > > ioctl. > > I think we can use snd_pcm_stop_xrun() for this purpose. Right. But beware of locking by this function. Unlike snd_pcm_stop() this function takes the stream lock by itself. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
