On Thu, 22 Oct 2020 15:24:12 +0200, Maxime Ripard wrote: > > Hi Takashi, > > On Thu, Oct 22, 2020 at 03:20:49PM +0200, Takashi Iwai wrote: > > On Thu, 22 Oct 2020 14:57:41 +0200, > > Maxime Ripard wrote: > > > > > > On Thu, Oct 22, 2020 at 12:03:19PM +0200, Jaroslav Kysela wrote: > > > > Dne 22. 10. 20 v 11:50 Maxime Ripard napsal(a): > > > > > > > > > So, I'm not really sure what I'm supposed to do here. The drivers > > > > > involved don't appear to be doing anything extraordinary, but the issues > > > > > lockdep report are definitely valid too. What are the expectations in > > > > > terms of context from ALSA when running the callbacks, and how can we > > > > > fix it? > > > > > > > > I think that you should set the non-atomic flag and wake up the workqueue or > > > > so from interrupt handler in this case. Call snd_pcm_period_elapsed() from the > > > > workqueue not the interrupt handler context. > > > > > > Yeah, that was my first guess too. However, the DMA driver uses some > > > kind of generic helpers using a tasklet, so getting rid of it would take > > > some work and would very likely not be eligible for stable. > > > > Who sets the nonatomic flag for vc4? I couldn't find the relevant > > code in the latest upstream. > > Sorry if this wasn't clear enough, it's not there at the moment, ALSA > takes a spinlock and lockdep complains that we're sleeping in an atomic > context. > > I tried to add the nonatomic flag in my tree to see if it was fixing the > issue, but ran into another lockdep complain now with ALSA taking a > mutex in a tasklet. I see, thanks for clarification. > > Ideally dmaengine PCM helper should support the nonatomic mode, but > > until then, the other side needs to drop the nonatomic flag, I > > suppose. > > In this case, I'm not sure the blame is in the PCM helper but if there's > any blame, I guess it's the virt-chan layer inside dmaengine (so for > providers) that use a tasklet instead of something that allows sleeping Well, we have to align either to atomic or non-atomic operation. If we want to solve solely in vc4, the fix would be to make the trigger action into some own work. Takashi
