[PATCH] dmaengine: pxa_dma: implement device_synchronize

[Vinod Koul]

On Sun, Jul 10, 2016 at 11:50:49PM +0200, Robert Jarzmik wrote:
> Implement the function which wait until a dma channel is stopped to have
> a synchronization point.
> 
> This also protects the pxad_remove() from races, such as spurious
> interrupts while removing the driver, because :
>  - as long as there is one dma channel requested, ie. dma_chan_get() but
>    no dma_chan_put(), the try_module_get() of dma_chan_get() prevents
>    the remove() routine from running
>  - when the last channel is released, ie. the last dma_chan_put() is
>    called, if there is a running DMA, pxad_synchronize() is called
>  - pxad_synchronize() waits for the channel to stop, which in turn
>    ensures on pxa architecture that the interrupt cannot be fired anymore

Applied, thanks

-- 
~Vinod