On 10/14/2015 12:50 PM, Vinod Koul wrote: > 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. That does not match reality though. Which means the documentation is wrong. Pretty much all drivers implement a non-synchronous terminate function and there are users that rely on this. -- 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
