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>
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index acfd0f7..aaac4fb 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -778,8 +778,16 @@
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;
}