[PATCH] ASoC: rockchip: i2s: Fix crash on missing pinctrl

[Chen-Yu Tsai <wens@kernel.org>]

From: Chen-Yu Tsai <wens@csie.org>

Commit 44f362c2cc6d ("ASoC: rockchip: i2s: switch BCLK to GPIO") added
pinctrl lookups, but did not skip the lookup if there was no pinctrl
device tied to the I2S controller. As a result, the lookup was done
on an invalid pointer in such cases, causing a kernel panic.

Only do the subsequent pinctrl state lookups and switch if a pinctrl
device was found.

i2s_pinctrl_select_bclk_{on,off} already guard against missing pinctrl
device or pinctrl state, so those two functions aren't touched.

Fixes: 44f362c2cc6d ("ASoC: rockchip: i2s: switch BCLK to GPIO")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---

This is based on next-20220621, which just saw the inclusion of the
commit this patch fixes.

This issue was found and tested on ROC-RK3328-CC. Tried to test on
RK3399, but that has some other DRM driver related crash.

 sound/soc/rockchip/rockchip_i2s.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/sound/soc/rockchip/rockchip_i2s.c b/sound/soc/rockchip/rockchip_i2s.c
index be051e48b97b..9fa8ffd712ea 100644
--- a/sound/soc/rockchip/rockchip_i2s.c
+++ b/sound/soc/rockchip/rockchip_i2s.c
@@ -808,24 +808,23 @@ static int rockchip_i2s_probe(struct platform_device *pdev)
 
 	i2s->bclk_ratio = 64;
 	i2s->pinctrl = devm_pinctrl_get(&pdev->dev);
-	if (IS_ERR(i2s->pinctrl))
+	if (IS_ERR(i2s->pinctrl)) {
 		dev_err(&pdev->dev, "failed to find i2s pinctrl\n");
+	} else {
+		i2s->bclk_on = pinctrl_lookup_state(i2s->pinctrl, "bclk_on");
+		if (IS_ERR_OR_NULL(i2s->bclk_on))
+			dev_err(&pdev->dev, "failed to find i2s default state\n");
+		else
+			dev_dbg(&pdev->dev, "find i2s bclk state\n");
 
-	i2s->bclk_on = pinctrl_lookup_state(i2s->pinctrl,
-				   "bclk_on");
-	if (IS_ERR_OR_NULL(i2s->bclk_on))
-		dev_err(&pdev->dev, "failed to find i2s default state\n");
-	else
-		dev_dbg(&pdev->dev, "find i2s bclk state\n");
-
-	i2s->bclk_off = pinctrl_lookup_state(i2s->pinctrl,
-				  "bclk_off");
-	if (IS_ERR_OR_NULL(i2s->bclk_off))
-		dev_err(&pdev->dev, "failed to find i2s gpio state\n");
-	else
-		dev_dbg(&pdev->dev, "find i2s bclk_off state\n");
+		i2s->bclk_off = pinctrl_lookup_state(i2s->pinctrl, "bclk_off");
+		if (IS_ERR_OR_NULL(i2s->bclk_off))
+			dev_err(&pdev->dev, "failed to find i2s gpio state\n");
+		else
+			dev_dbg(&pdev->dev, "find i2s bclk_off state\n");
 
-	i2s_pinctrl_select_bclk_off(i2s);
+		i2s_pinctrl_select_bclk_off(i2s);
+	}
 
 	i2s->playback_dma_data.addr = res->start + I2S_TXDR;
 	i2s->playback_dma_data.addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
-- 
2.34.1