Re: [PATCH v2.6.38-rc7] Revert "libata: ahci_start_enginecompliant to AHCI spec"

From: Tejun Heo
Date: Fri May 20 2011 - 11:43:51 EST


On Fri, May 20, 2011 at 11:40:20AM -0400, Valdis.Kletnieks@xxxxxx wrote:
> On Wed, 18 May 2011 17:14:56 PDT, Jian Peng said:
>
> > > @@ -1353,6 +1332,8 @@
> > >
> > >
> > > ahci_start_engine(ap);
> > >
> > > + msleep(5);
> > > +
> > > if (online)
> > >
> > > *class = ahci_dev_classify(ap);
> > >
>
> It may very well be that adding a magic msleep(5) here just Makes It Work, but
> I have a gut feeling that it's in the wrong place (for starters, 'online' can't change
> during the msleep() unless somebody *else* sets it - in which case the locking
> is screwed up as we're not forcing a re-read of the value). The msleep() probably
> needs to be before something else further down in the code (but I have no idea
> exactly what).

At this point, I think it would be better to simply add a flag and
enable the check for the affected controller.

Thanks.

--
tejun
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