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authorLukasz Dorau <lukasz.dorau@intel.com>2013-10-14 18:18:53 +0200
committerTejun Heo <tj@kernel.org>2013-10-15 15:39:57 +0200
commitfa070ee6dc70bcc19737a2406d741b089b3149d5 (patch)
tree473e3c82fd89791131c0d051a378f9178443f002 /drivers/ata
parentlibata: make ata_eh_qc_retry() bump scmd->allowed on bogus failures (diff)
downloadlinux-fa070ee6dc70bcc19737a2406d741b089b3149d5.tar.xz
linux-fa070ee6dc70bcc19737a2406d741b089b3149d5.zip
libahci: fix turning on LEDs in ahci_start_port()
If EM Transmit bit is busy during init ata_msleep() is called. It is wrong - msleep() should be used instead of ata_msleep(), because if EM Transmit bit is busy for one port, it will be busy for all other ports too, so using ata_msleep() causes wasting tries for another ports. The most common scenario looks like that now (six ports try to transmit a LED meaasege): - port #0 tries for the 1st time and succeeds - ports #1-5 try for the 1st time and sleeps - port #1 tries for the 2nd time and succeeds - ports #2-5 try for the 2nd time and sleeps - port #2 tries for the 3rd time and succeeds - ports #3-5 try for the 3rd time and sleeps - port #3 tries for the 4th time and succeeds - ports #4-5 try for the 4th time and sleeps - port #4 tries for the 5th time and succeeds - port #5 tries for the 5th time and sleeps At this moment port #5 wasted all its five tries and failed to initialize. Because there are only 5 (EM_MAX_RETRY) tries available usually only five ports succeed to initialize. The sixth port and next ones usually will fail. If msleep() is used instead of ata_msleep() the first port succeeds to initialize in the first try and next ones usually succeed to initialize in the second try. tj: updated comment Signed-off-by: Lukasz Dorau <lukasz.dorau@intel.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'drivers/ata')
-rw-r--r--drivers/ata/libahci.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index acfd0f711069..aaac4fb0d564 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -778,8 +778,16 @@ static void ahci_start_port(struct ata_port *ap)
rc = ap->ops->transmit_led_message(ap,
emp->led_state,
4);
+ /*
+ * If busy, give a breather but do not
+ * release EH ownership by using msleep()
+ * instead of ata_msleep(). EM Transmit
+ * bit is busy for the whole host and
+ * releasing ownership will cause other
+ * ports to fail the same way.
+ */
if (rc == -EBUSY)
- ata_msleep(ap, 1);
+ msleep(1);
else
break;
}