On Fri, 2019-04-05 at 14:30 +0200, Takashi Iwai wrote: > On Thu, 04 Apr 2019 21:13:43 +0200, > Ranjani Sridharan wrote: > > > > > > + > > > > + /* set runtime config */ > > > > + runtime->hw.info = SNDRV_PCM_INFO_MMAP | > > > > + SNDRV_PCM_INFO_MMAP_VALID | > > > > + SNDRV_PCM_INFO_INTERLEAVED | > > > > + SNDRV_PCM_INFO_PAUSE | > > > > + SNDRV_PCM_INFO_RESUME | > > > > + SNDRV_PCM_INFO_NO_PERIOD_WAKEUP; > > > > > > Does SOF support the full resume? That is, the stream gets > > > resumed > > > at > > > the exact position that was suspended. Most devices can't, hence > > > they > > > don't set *_INFO_RESUME flag and let user-space restarting. > > > > Hi Takashi, > > > > Thanks for your comment. The SOF driver definitely cannot guarantee > > to > > resume from the exact same position due to the fact that triggers > > for > > the host dma and link dma are not synchronized and also IPC > > scheduling > > will affect this. So we should remove INOF_RESUME from hw.info. > > > > I do one follow up question for you. When a stream resumes/restarts > > after suspend, we have the need for restoring the hw_params in the > > SOF > > driver prior to handling the START trigger. I noticed that the > > legacy/skylake driver does not seem to do this though. Do you have > > any > > insights on what we might be missing in the SOF driver? > > So, SOF mandates the re-setup of the hw params in BE at resume? Yes. That's correct. > Then the right place to do is in the prepare callback. Without > SNDRV_PCM_INFO_RESUME flag, the PCM core won't trigger RESUME, but > returns -ENOSYS. Then user-space will do prepare, and start with the > normal trigger. > > You'd need a flag indicating the BE hw_params resetup, and at the > beginning of prepare function, the flag is checked and the (internal) > hw_params is done accordingly. This makes sense. Thank you for your help. We will change the flow accordingly. Thanks, Ranjani > > > Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
