On 07/18/16 13:34, Russell King - ARM Linux wrote: > On Thu, Jul 14, 2016 at 03:42:37PM +0300, Peter Ujfalusi wrote: >> 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. > -- Péter -- 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
