dma: mmp_pdma: only complete one transaction from dma_do_tasklet() (b721f9e8) · Commits · 戴 / test

Currently, when an interrupt has occured for a channel, the tasklet worker code will only look at the very last entry in the running list and complete its cookie, and then dispose the entire running chain. Hence, the first transaction's cookie will never complete. In fact, the interrupt we should handle will be the one related to the first descriptor in the chain with the ENDIRQEN bit set, so complete the second transaction that is in fact still running. As a result, the driver can't currently handle multiple transactions on one chanel, and it's likely that no drivers exist that rely on this feature. Fix this by walking the running_chain and look for the first descriptor that has the interrupt-enable bit set. Only queue descriptors up to that point for completion handling, while leaving the rest intact. Also, only make the channel idle if the list is completely empty after such a cycle. Signed-off-by:

Daniel Mack <zonque@gmail.com> Signed-off-by:

Vinod Koul <vinod.koul@intel.com>

drivers/dma/mmp_pdma.c

+21 −14

Original line number	Diff line number	Diff line
		@@ -703,25 +703,32 @@ static void dma_do_tasklet(unsigned long data)

		spin_lock_irqsave(&chan->desc_lock, flags);

		/* update the cookie if we have some descriptors to cleanup */
		if (!list_empty(&chan->chain_running)) {
		dma_cookie_t cookie;
		list_for_each_entry_safe(desc, _desc, &chan->chain_running, node) {
		/*
		* move the descriptors to a temporary list so we can drop
		* the lock during the entire cleanup operation
		*/
		list_del(&desc->node);
		list_add(&desc->node, &chain_cleanup);

		desc = to_mmp_pdma_desc(chan->chain_running.prev);
		cookie = desc->async_tx.cookie;
		/*
		* Look for the first list entry which has the ENDIRQEN flag
		* set. That is the descriptor we got an interrupt for, so
		* complete that transaction and its cookie.
		*/
		if (desc->desc.dcmd & DCMD_ENDIRQEN) {
		dma_cookie_t cookie = desc->async_tx.cookie;
		dma_cookie_complete(&desc->async_tx);

		dev_dbg(chan->dev, "completed_cookie=%d\n", cookie);
		break;
		}
		}

		/*
		* move the descriptors to a temporary list so we can drop the lock
		* during the entire cleanup operation
		* The hardware is idle and ready for more when the
		* chain_running list is empty.
		*/
		list_splice_tail_init(&chan->chain_running, &chain_cleanup);

		/* the hardware is now idle and ready for more */
		chan->idle = true;
		chan->idle = list_empty(&chan->chain_running);

		/* Start any pending transactions automatically */
		start_pending_queue(chan);

Admin message