[PATCH] ASoC: max98090: fix missing IS_ERR() before PTR_ERR() on mclk lookup

[Uday Khare <udaykhare77@gmail.com>]

In max98090_probe(), the -EPROBE_DEFER check after devm_clk_get() is
broken due to a missing IS_ERR() guard.

The code intends to return -EPROBE_DEFER only when the clock lookup
fails with that specific error.  However, without IS_ERR() the check:

    if (PTR_ERR(max98090->mclk) == -EPROBE_DEFER)

is called unconditionally, including when devm_clk_get() succeeds and
returns a valid pointer.  Calling PTR_ERR() on a valid pointer
reinterprets its address as a signed long; the result is arbitrary
and is almost never equal to -EPROBE_DEFER, so the check silently
does nothing in the success case.  When devm_clk_get() fails with
any error other than -EPROBE_DEFER the check is also skipped, leaving
max98090->mclk holding an error pointer with no indication to the caller.

This means a deferred probe will never actually be triggered for this
device, and any non-EPROBE_DEFER clock error is silently swallowed with
the error pointer left in the mclk field.

Fix this by adding the missing IS_ERR() guard around the PTR_ERR() call,
matching the pattern already used in the sibling max98088 and wm8960
drivers.

Fixes: b10ab7b838bd ("ASoC: max98090: Add master clock handling")
Signed-off-by: Uday Khare <udaykhare77@gmail.com>
---
 sound/soc/codecs/max98090.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/max98090.c b/sound/soc/codecs/max98090.c
index 8c9d09c21e64..720ea85e0bf5 100644
--- a/sound/soc/codecs/max98090.c
+++ b/sound/soc/codecs/max98090.c
@@ -2423,8 +2423,9 @@ static int max98090_probe(struct snd_soc_component *component)
 	dev_dbg(component->dev, "max98090_probe\n");
 
 	max98090->mclk = devm_clk_get(component->dev, "mclk");
-	if (PTR_ERR(max98090->mclk) == -EPROBE_DEFER)
-		return -EPROBE_DEFER;
+	if (IS_ERR(max98090->mclk))
+		if (PTR_ERR(max98090->mclk) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
 
 	max98090->component = component;
 
-- 
2.55.0