dmaengine: dmatest: Add support for completion polling

With the polled parameter the DMA drivers can be tested if they can work
correctly when no completion is requested (no DMA_PREP_INTERRUPT and no
callback is provided).

If polled mode is selected then use dma_sync_wait() to execute the test
iteration instead of relying on the completion callback.

Signed-off-by: Peter Ujfalusi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/dmatest.c

···
 module_param(norandom, bool, 0644);
 MODULE_PARM_DESC(norandom, "Disable random offset setup (default: random)");
 
+static bool polled;
+module_param(polled, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(polled, "Use polling for completion instead of interrupts");
+
 static bool verbose;
 module_param(verbose, bool, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(verbose, "Enable \"success\" result messages (default: off)");
···
 	bool		norandom;
 	int		alignment;
 	unsigned int	transfer_size;
+	bool		polled;
 };
 
 /**
···
 	/*
 	 * src and dst buffers are freed by ourselves below
 	 */
-	flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
+	if (params->polled)
+		flags = DMA_CTRL_ACK;
+	else
+		flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
 
 	ktime = ktime_get();
 	while (!kthread_should_stop()
···
 		}
 
 		done->done = false;
-		tx->callback = dmatest_callback;
-		tx->callback_param = done;
+		if (!params->polled) {
+			tx->callback = dmatest_callback;
+			tx->callback_param = done;
+		}
 		cookie = tx->tx_submit(tx);
 
 		if (dma_submit_error(cookie)) {
···
 			msleep(100);
 			goto error_unmap_continue;
 		}
-		dma_async_issue_pending(chan);
 
-		wait_event_freezable_timeout(thread->done_wait, done->done,
-					     msecs_to_jiffies(params->timeout));
+		if (params->polled) {
+			status = dma_sync_wait(chan, cookie);
+			dmaengine_terminate_sync(chan);
+			if (status == DMA_COMPLETE)
+				done->done = true;
+		} else {
+			dma_async_issue_pending(chan);
 
-		status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
+			wait_event_freezable_timeout(thread->done_wait,
+					done->done,
+					msecs_to_jiffies(params->timeout));
+
+			status = dma_async_is_tx_complete(chan, cookie, NULL,
+							  NULL);
+		}
 
 		if (!done->done) {
 			result("test timed out", total_tests, src->off, dst->off,
···
 	params->norandom = norandom;
 	params->alignment = alignment;
 	params->transfer_size = transfer_size;
+	params->polled = polled;
 
 	request_channels(info, DMA_MEMCPY);
 	request_channels(info, DMA_MEMSET);