[PATCH] sound: caiaq: input: Add error handling for unsupported input methods in `snd_usb_caiaq_input_init`

[Ruliang Lin]

Smatch complains that:
snd_usb_caiaq_input_init() warn: missing error code 'ret'

This patch adds a new case to handle the situation where the 
device does not support any input methods in the 
`snd_usb_caiaq_input_init` function. It returns an `-EINVAL` error code 
to indicate that no input methods are supported on the device.

Fixes: 523f1dce3743 ("[ALSA] Add Native Instrument usb audio device support")
Signed-off-by: Ruliang Lin <u202112092@xxxxxxxxxxx>
Reviewed-by: Dongliang Mu <dzm91@xxxxxxxxxxx>
---
The issue is found by static analyzer. The patched code has passed
Smatch checker, but remains untested on real device.
---
 sound/usb/caiaq/input.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/usb/caiaq/input.c b/sound/usb/caiaq/input.c
index 1e2cf2f08eec..84f26dce7f5d 100644
--- a/sound/usb/caiaq/input.c
+++ b/sound/usb/caiaq/input.c
@@ -804,6 +804,7 @@ int snd_usb_caiaq_input_init(struct snd_usb_caiaqdev *cdev)
 
 	default:
 		/* no input methods supported on this device */
+		ret = -EINVAL;
 		goto exit_free_idev;
 	}
 
-- 
2.25.1