Re: [PATCH] libata: always use polling SETXFER

[Jeff Garzik <jeff@garzik.org>]

Tejun Heo wrote:
> Several people have reported LITE-ON LTR-48246S detection failed
> because SETXFER fails.  It seems the device raises IRQ too early after
> SETXFER.  This is controller independent.  The same problem has been
> reported for different controllers.
> 
> So, now we have pata_via where the controller raises IRQ before it's
> ready after SETXFER and a device which does similar thing.  This patch
> makes libata always execute SETXFER via polling.  As this only happens
> during EH, performance impact is nil.  Setting ATA_TFLAG_POLLING is
> also moved from issue hot path to ata_dev_set_xfermode() - the only
> place where SETXFER can be issued.
> 
> Note that ATA_TFLAG_POLLING applies only to drivers which implement
> SFF TF interface and use libata HSM.  More advanced controllers ignore
> the flag.  This doesn't matter for this fix as SFF TF controllers are
> the problematic ones.
> 
> Signed-off-by: Tejun Heo <htejun@gmail.com>
> ---
>  drivers/ata/libata-core.c |   13 ++++---------
>  drivers/ata/pata_via.c    |   12 ++++++------
>  include/linux/libata.h    |    1 -
>  3 files changed, 10 insertions(+), 16 deletions(-)

To Linus and Andrew:

After discussion and a minor revision (mostly to the description), I am 
OK with this patch.

At this point, I am only reluctant to push it for 2.6.22 since it is so 
late in the -rc series.

If we have another -rc, I would probably be OK with pushing it for 
2.6.22, otherwise I would prefer to wait for 2.6.23.

Comments solicited, from all involved...

	Jeff