On Tue, 21 May 2024 20:32:59 +0200, Mark Brown wrote: > > On Tue, May 21, 2024 at 10:31:12AM +0200, Louis Chauvet wrote: > > > To address this DMA issue, I have created a patch [1] that guarantees the > > completion of the DMA transfer upon the return of xdma_synchronize. This > > means xdma_synchronize now sleeps, but looking at other drivers around it > > appears expected to be able to do so. > > You need to set the nonatomic flag for the PCM to allow this, the > default is that triggers run in atomic context. Right, that's a most straightforward solution. It implies that the period updates must be in non-atomic, i.e. use a threaded irq handler in most cases. If the synchronization is needed for assuring the hardware stop, there is an alternative with PCM sync_stop callback, too. The callback is called at each time after a stream gets stopped before the next action (that is, either prepare, hw_params or close). It's only for stopping, and there is no similar way for sync of a stream start, though. thanks, Takashi
