[PATCH] Fix HD activity LED with ahci

Patch: fix wrong HD activity control by ahci driver

The ahci driver 1.0 sets the SActive bit on every transaction,
causing the LED to light up. The SActive bit is used only for
native command queuing (NCQ) which the current driver version
doesn't implement. Resetting the SActive bit is the device's
responsibility (by sending a "Set Device Bits FIS" to the
host adapter) but this is not required in response to
non-NCQ commands, and (most) devices don't. Thus the LED
stays always on. This patch fixes the LED behavior.

Spec references:
http://www.intel.com/technology/serialata/pdf/rev1_1.pdf, sec. 3.3.13, 5.5.1
http://www.serialata.org/docs/serialata10a.pdf
http://www.intel.com/design/storage/papers/25266401.pdf

Signed-off-by: Martin.Wilck@fujitsu-siemens.com
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 0c79cafb1348c9b6968ef6bcc09b3e8e55eb5176..0b228ff671439fedc0a24a10afd2e1f6b7215aa7 100644 (file)
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -698,9 +698,6 @@ static int ahci_qc_issue(struct ata_queued_cmd *qc)
        struct ata_port *ap = qc->ap;
        void *port_mmio = (void *) ap->ioaddr.cmd_addr;
 
-       writel(1, port_mmio + PORT_SCR_ACT);
-       readl(port_mmio + PORT_SCR_ACT);        /* flush */
-
        writel(1, port_mmio + PORT_CMD_ISSUE);
        readl(port_mmio + PORT_CMD_ISSUE);      /* flush */