linux-kernel - snd_intel8x0m: error message because return value is unused?

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Date:	Tue, 22 Feb 2011 00:57:22 +0100
From:	Paul Bolle <pebolle@...cali.nl>
To:	linux-kernel@...r.kernel.org
Subject: snd_intel8x0m: error message because return value is unused?

0) In order to make a laptop run without error messages (ie, printks at
KERN_ERR level) I had to look at an error generated by snd_intel8x0m:

     ALSA intel8x0m.c:904: AC'97 warm reset still in progress? [0x2]

1) There's a datasheet one can study to understand that message. But
that seems not necessary here. It all boils down to the fact that this
test:

    if ((igetdword(chip, ICHREG(GLOB_CNT)) & ICH_AC97WARM) == 0)
            goto __ok;

will always fail so we'll never go to __ok and finally that error will
be printed. But if I simply change it into:

    cnt = igetdword(chip, ICHREG(GLOB_CNT));
    if ((cnt & ICH_AC97WARM) == 0)
            goto __ok;

this test will (always) succeed, we'll go to __ok and no error message
will be printed. So apparently, the error message was just a false
alarm.

2) Before I submit a (trivial) patch to fix this I'd like to better
understand what is going on here: is this standard C behavior, something
the build system asks the compiler to do, or maybe something else?

Paul Bolle

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