[PATCH -next] ASoC: sh: rz-ssi: Fix return value check in rz_ssi_dma_request()

[Yang Yingliang]

In case of error, the function dma_request_chan() returns ERR_PTR()
and never returns NULL. Set 'dma_ch' to NULL, if dma_request_chan()
returns error, so the code using 'dma_ch' can work correctly.

Fixes: 26ac471c5354 ("ASoC: sh: rz-ssi: Add SSI DMAC support")
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
 sound/soc/sh/rz-ssi.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c
index ea8d33ede5d2..5ec78fd94d94 100644
--- a/sound/soc/sh/rz-ssi.c
+++ b/sound/soc/sh/rz-ssi.c
@@ -676,11 +676,17 @@ 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;
 	}
-- 
2.25.1