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author | Lukasz Dorau <lukasz.dorau@intel.com> | 2013-10-14 18:18:53 +0200 |
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committer | Tejun Heo <tj@kernel.org> | 2013-10-15 15:39:57 +0200 |
commit | fa070ee6dc70bcc19737a2406d741b089b3149d5 (patch) | |
tree | 473e3c82fd89791131c0d051a378f9178443f002 /drivers/ata/libahci.c | |
parent | libata: make ata_eh_qc_retry() bump scmd->allowed on bogus failures (diff) | |
download | linux-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/libahci.c')
-rw-r--r-- | drivers/ata/libahci.c | 10 |
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; } |