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Date: Mon, 14 Oct 2013 18:18:53 +0200 From: Lukasz Dorau <lukasz.dorau@...el.com> To: tj@...nel.org Cc: linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH 2] 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. Signed-off-by: Lukasz Dorau <lukasz.dorau@...el.com> --- drivers/ata/libahci.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index acfd0f7..8fb7092 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -779,7 +779,11 @@ static void ahci_start_port(struct ata_port *ap) emp->led_state, 4); if (rc == -EBUSY) - ata_msleep(ap, 1); + /* Do not release ownership of @ap's EH, + * because EM Transmit bit is busy for + * all ports sharing the @ap->host. + */ + msleep(1); else break; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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