| Date | Thu, 04 Dec 2008 13:20:15 +0900 | From | Tejun Heo <> | Subject | Re: [patch 067/104] libata: improve phantom device detection |
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> 2.6.27-stable review patch. If anyone has any objections, please let us know. > > ------------------ > From: Tejun Heo <tj@kernel.org> > > commit 6a6b97d360702b98c02c7fca4c4e088dcf3a2985 upstream. > > Currently libata uses four methods to detect device presence. > > 1. PHY status if available. > 2. TF register R/W test (only promotes presence, never demotes) > 3. device signature after reset > 4. IDENTIFY failure detection in SFF state machine > > Combination of the above works well in most cases but recently there > have been a few reports where a phantom device causes unnecessary > delay during probe. In both cases, PHY status wasn't available. In > one case, it passed #2 and #3 and failed IDENTIFY with ATA_ERR which > didn't qualify as #4. The other failed #2 but as it passed #3 and #4, > it still caused failure. > > In both cases, phantom device reported diagnostic failure, so these > cases can be safely worked around by considering any !ATA_DRQ IDENTIFY > failure as NODEV_HINT if diagnostic failure is set. > > Signed-off-by: Tejun Heo <tj@kernel.org> > Signed-off-by: Jeff Garzik <jgarzik@redhat.com> > Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Alan thinks this patch could cause regression. Given that we're nearing the end of 2.6.28-rc cycles, I don't think it's critical to include this into 2.6.27-stable or at least it can wait a bit more.
Thanks.
-- tejun
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