From fa070ee6dc70bcc19737a2406d741b089b3149d5 Mon Sep 17 00:00:00 2001 From: Lukasz Dorau Date: Mon, 14 Oct 2013 18:18:53 +0200 Subject: [PATCH] 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 Signed-off-by: Tejun Heo --- drivers/ata/libahci.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index acfd0f711069e9..aaac4fb0d5645f 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; }