On 07/18/16 13:34, Russell King - ARM Linux wrote:

On Thu, Jul 14, 2016 at 03:42:37PM +0300, Peter Ujfalusi wrote:

quoted

Before looking for the next descriptor to start, complete the just finished
cookie.

This change will reduce performance as we no longer have an overlap
between the next request starting to be dealt with in the hardware
vs the previous request being completed.

vchan_cookie_complete() will only mark the cookie completed, adds the vd to
the desc_completed list (it was deleted from desc_issued list when it was
started by omap_dma_start_desc) and schedule the tasklet to deal with the real
completion later.
Marking the just finished descriptor/cookie done first then looking for
possible descriptors in the queue to start feels like a better sequence.

After a quick grep in the kernel source: only omap-dma.c was starting the next
transfer before marking the current completed descriptor/cookie done.

Your commit log doesn't
say _why_ the change is being made, it merely tells us what the
patch is doing, which we can see already.

Please describe changes a little better.

-- 
P?ter