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