From: Lukasz Dorau <lukasz.dorau@intel.com>
To: tj@kernel.org
Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] libahci: fix turning on LEDs in ahci_start_port()
Date: Mon, 14 Oct 2013 14:58:19 +0200 [thread overview]
Message-ID: <20131014125819.19262.32922.stgit@gklab-154-244.igk.intel.com> (raw)
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.
Signed-off-by: Lukasz Dorau <lukasz.dorau@intel.com>
---
drivers/ata/libahci.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index acfd0f7..cf38692 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -779,7 +779,7 @@ static void ahci_start_port(struct ata_port *ap)
emp->led_state,
4);
if (rc == -EBUSY)
- ata_msleep(ap, 1);
+ msleep(1);
else
break;
}
next reply other threads:[~2013-10-14 12:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-14 12:58 Lukasz Dorau [this message]
2013-10-14 13:20 ` Tejun Heo
2013-10-14 16:15 ` Dorau, Lukasz
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