On Thu, Oct 08, 2015 at 04:51:30PM +0200, Lars-Peter Clausen wrote: > > The DMA engine API states that > > > > * device_terminate_all > > - Aborts all the pending and ongoing transfers on the channel > > - This command should operate synchronously on the channel, > > terminating right away all the channels > > > > I wonder how to interpret "synchronously" here, should terminate_all() wait > > for termination to be complete ? In that case it wouldn't be valid to call it > > from non-sleepable context. > > We need to extend the DMAengine API to allow synchronization. The issue is > not only the IRQ itself but also the tasklet that can be scheduled from the > IRQ. Since we in some cases (e.g. audio underrun) call terminate_all() from > within the completion callback that runs in the in the tasklet we can't > synchronize to the tasklet in dmaengine_terminate_all(). We need a separate > API call to handle this. And then maybe have a helper like > dmaengine_terminate_all_sync() that terminates and synchronizes. And in > cases where terminate_all is called from a context where it can't > synchronize the new API needs to be called separately before freeing the > resources. Right now the terminate_all() is intended for syncronous behaviour which prevents it from being invoked in the callback. I do agree that we should add separate call to abort the txn only and use this for abort behaviour when we want to close down.. > > I've talked about this in the past here: > http://mailman.alsa-project.org/pipermail/alsa-devel/2013-October/067155.html -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
