[PATCH] ALSA: usb-audio: scarlett2: Fix for loop increment in scarlett2_usb_get_config

Nathan Chancellor
2021-06-24T21:21:59Z

Clang warns:

sound/usb/mixer_scarlett_gen2.c:1189:32: warning: expression result
unused [-Wunused-value]
for (i = 0; i < count; i++, (u16 *)buf++)
^ ~~~~~
1 warning generated.

It appears the intention was to cast the void pointer to a u16 pointer
so that the data could be iterated through like an array of u16 values.
However, the cast happens after the increment because a cast is an
rvalue, whereas the post-increment operator only works on lvalues, so
the loop does not iterate as expected.

Replace the post-increment shorthand with the full expression so the
cast can be added in the right place and the look works as expected.

Fixes: ac34df733d2d ("ALSA: usb-audio: scarlett2: Update get_config to do endian conversion")
Link: https://github.com/ClangBuiltLinux/linux/issues/1408
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
sound/usb/mixer_scarlett_gen2.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c
index fcba682cd422..c20c7f1ddc50 100644
--- a/sound/usb/mixer_scarlett_gen2.c
+++ b/sound/usb/mixer_scarlett_gen2.c
@@ -1186,7 +1186,7 @@ static int scarlett2_usb_get_config(
if (err < 0)
return err;
if (size == 2)
- for (i = 0; i < count; i++, (u16 *)buf++)
+ for (i = 0; i < count; i++, buf = (u16 *)buf + 1)
*(u16 *)buf = le16_to_cpu(*(__le16 *)buf);
return 0;
}

base-commit: 5c89c2c7fbfa9124dd521c375b9c82b9ed75bc28
--
2.32.0.93.g670b81a890