[PATCH v2] ASoC: sh: rz-ssi: Improve error handling in rz_ssi_dma_request function

[Biju Das <biju.das.jz@xxxxxxxxxxxxxx>]

The pointer returned by the dma_request_chan function is an error pointer
for the error cases. But on the rz_ssi_dma_request function, it checks for
NULL pointer instead.

This patch fixes the issue by checking the error pointer instead of NULL
pointer.

Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
v1->v2:
 * Replaced IS_ERR_OR_NULL with IS_ERR for error pointer check, as the
   dma_request_chan function never returns NULL pointer for error case.
---
 sound/soc/sh/rz-ssi.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c
index ea8d33ede5d2..2f9345415a15 100644
--- a/sound/soc/sh/rz-ssi.c
+++ b/sound/soc/sh/rz-ssi.c
@@ -676,11 +676,19 @@ static void rz_ssi_release_dma_channels(struct rz_ssi_priv *ssi)
 static int rz_ssi_dma_request(struct rz_ssi_priv *ssi, struct device *dev)
 {
 	ssi->playback.dma_ch = dma_request_chan(dev, "tx");
+	if (IS_ERR(ssi->playback.dma_ch))
+		ssi->playback.dma_ch = NULL;
+
 	ssi->capture.dma_ch = dma_request_chan(dev, "rx");
+	if (IS_ERR(ssi->capture.dma_ch))
+		ssi->capture.dma_ch = NULL;
+
 	if (!ssi->playback.dma_ch && !ssi->capture.dma_ch) {
 		ssi->playback.dma_ch = dma_request_chan(dev, "rt");
-		if (!ssi->playback.dma_ch)
+		if (IS_ERR(ssi->playback.dma_ch)) {
+			ssi->playback.dma_ch = NULL;
 			goto no_dma;
+		}
 
 		ssi->dma_rt = true;
 	}
-- 
2.17.1