From fa14e851ddc9049b39271980e2d24734c0c477e3 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 13 Nov 2008 10:04:46 +0900 Subject: libata: improve phantom device detection 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 Signed-off-by: Jeff Garzik Signed-off-by: Greg Kroah-Hartman --- drivers/ata/libata-sff.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c index 2a4c516894f0..bb26a26f3bf6 100644 --- a/drivers/ata/libata-sff.c +++ b/drivers/ata/libata-sff.c @@ -1227,10 +1227,19 @@ fsm_start: /* ATA PIO protocol */ if (unlikely((status & ATA_DRQ) == 0)) { /* handle BSY=0, DRQ=0 as error */ - if (likely(status & (ATA_ERR | ATA_DF))) + if (likely(status & (ATA_ERR | ATA_DF))) { /* device stops HSM for abort/error */ qc->err_mask |= AC_ERR_DEV; - else { + + /* If diagnostic failed and this is + * IDENTIFY, it's likely a phantom + * device. Mark hint. + */ + if (qc->dev->horkage & + ATA_HORKAGE_DIAGNOSTIC) + qc->err_mask |= + AC_ERR_NODEV_HINT; + } else { /* HSM violation. Let EH handle this. * Phantom devices also trigger this * condition. Mark hint. -- cgit v1.2.3