On Fri, 2006-01-12 at 02:07 -0500, James C Georgas wrote:
> /**
> * snd_ac97_update_bits - update the bits on the given register
> * @ac97: the ac97 instance
> * @reg: the register to change
> * @mask: the bit-mask to change
> * @value: the value to set
> *
> * Updates the masked-bits on the given register only when the value
> * is changed.
> *
> * Returns 1 if the bits are changed, 0 if no change, or a negative
> * code on failure.
> */
>
> If the intent is to update _only_ the bits given in the mask, as the
> comment seems to suggest, then the current code won't do it.
>
> Specifically, it'll clobber unset bits that are _not_ in the mask, if
> the new bit is set. Here's a fix:
>
> diff -r bc7ef767d0cf pci/ac97/ac97_codec.c
> --- a/pci/ac97/ac97_codec.c Wed Nov 29 15:29:40 2006 +0100
> +++ b/pci/ac97/ac97_codec.c Fri Dec 1 02:04:30 2006 -0500
> @@ -389,7 +389,7 @@ int snd_ac97_update_bits_nolock(struct s
> unsigned short old, new;
>
> old = snd_ac97_read_cache(ac97, reg);
> - new = (old & ~mask) | value;
> + new = (old & ~mask) | (value & mask);
> change = old != new;
> if (change) {
> ac97->regs[reg] = new;
> @@ -406,7 +406,7 @@ static int snd_ac97_ad18xx_update_pcm_bi
>
> mutex_lock(&ac97->page_mutex);
> old = ac97->spec.ad18xx.pcmreg[codec];
> - new = (old & ~mask) | value;
> + new = (old & ~mask) | (value & mask);
> change = old != new;
> if (change) {
> mutex_lock(&ac97->reg_mutex);
>
bump...
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