[alsa-devel] [PATCH V3 2/4] AC97 driver for mpc5200

Grant Likely grant.likely at secretlab.ca
Mon May 25 18:00:57 CEST 2009

On Mon, May 25, 2009 at 9:21 AM, Jon Smirl <jonsmirl at gmail.com> wrote:
> On Mon, May 25, 2009 at 6:26 AM, Mark Brown
> <broonie at opensource.wolfsonmicro.com> wrote:
>>> +             spin_lock(&psc_dma->lock);
>>> +             out_be32(&psc_dma->psc_regs->ac97_slots, psc_dma->slots);
>>> +             spin_unlock(&psc_dma->lock);
>>> +             break;
>> This locking looks wrong - I'd expect it to also cover the modification
>> of psc_dma->slots?  Otherwise it's hard to see what it buys you.
> Grant, why are you spin locking around register access?

This lock/unlock is definitely bogus since a single register access is
already atomic.  Are there places in the code that I wrote where a
spin_lock/unlock is done around a single register access?


Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

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