dmaengine: add verification of DMA_INTERRUPT capability for dmatest

Looks like I forgot to add DMA_INTERRUPT cap setting to the idxd driver and
dmatest is still working regardless of this mistake. Add an explicit check
of DMA_INTERRUPT capability for dmatest to make sure the DMA device being used
actually supports interrupt before the test is launched and also that the
driver is programmed correctly.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/164978679251.2361020.5856734256126725993.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/dmatest.c

@@ -675,10 +675,16 @@ static int dmatest_func(void *data)
 	/*
 	 * src and dst buffers are freed by ourselves below
 	 */
-	if (params->polled)
+	if (params->polled) {
 		flags = DMA_CTRL_ACK;
-	else
-		flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
+	} else {
+		if (dma_has_cap(DMA_INTERRUPT, dev->cap_mask)) {
+			flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
+		} else {
+			pr_err("Channel does not support interrupt!\n");
+			goto err_pq_array;
+		}
+	}
 
 	ktime = ktime_get();
 	while (!(kthread_should_stop() ||
@@ -906,6 +912,7 @@ static int dmatest_func(void *data)
 	runtime = ktime_to_us(ktime);
 
 	ret = 0;
+err_pq_array:
 	kfree(dma_pq);
 err_srcs_array:
 	kfree(srcs);