Re: libata: cdrw/dvdrom disabed after s2ram (2.6.24-rc2)

[Andrew Morton <akpm@linux-foundation.org>]

> On Thu, 08 Nov 2007 14:49:33 -0500 Mark Lord <liml@rtr.ca> wrote:
> Andrew Morton wrote:
> >> On Thu, 8 Nov 2007 13:19:05 -0500 Jeff Garzik <jeff@garzik.org> wrote:
> >> On Thu, Nov 08, 2007 at 10:13:41AM -0800, Andrew Morton wrote:
> >>>> On Thu, 8 Nov 2007 13:02:56 -0500 Jeff Garzik <jeff@garzik.org> wrote:
> >>>> On Thu, Nov 08, 2007 at 09:49:58AM -0800, Andrew Morton wrote:
> ..
> >>> I suspect it wold be best to disable the feature for the 2.6.24 release,
> >>> then reenable it afterwards and keep doing this until the code is
> >>> sufficiently stable.
> >> Re-read my message :)
> >>
> >> The code is stable.  Behavior _by definition_ will vary by BIOS.
> >>
> >> This feature (a) enables suspend/resume, but (b) now sends random
> >> unvalidated shite to the device that we hope will work.
> >>
> >> Look at all the messages where turning on ACPI in libata _fixed_
> >> suspend/resume (because its obviously required for many, including
> >> laptops).
> > 
> > We fixed a somewhat-known number of machines and broke an unknown number. 
> > Linus will come after you with a pointy stick if he finds out.
> > 
> > Fixing previously-broken machines is nice, but breaking previously-working
> > ones gets people a lot more upset.
> > 
> >> So it's not an easy "turn it off" answer, you break shitloads of
> >> suspend/resume that way, that we just fixed.
> >>
> >> The message "_GTF unexpected object type" indicates a broken BIOS, so
> >> IMO we should proceed in that direction, blacklisting that platform.
> >>
> > 
> > Suggest that the feature be disabled until we have most of these
> > blacklistings in place.
> ..
> 
> The problem is, this code has already sat out the last release,
> and nobody noticed problems exactly because it was not enabled before.
> 
> If Jeff disables it again, then it will sit out another cycle without
> anybody exercising it.  At some point, we need to turn it on, and collect
> information about where there are problems (and fix them).
> 

We get a decent amount of testing during the -rc's.  I think it's OK to turn
a feature on during -rc and off for release while it gets settled in.

Hopefully Matthew's fix will address this particular problem.