From: David Milburn <dmilburn@redhat.com>
Date: Wed, 8 Apr 2009 11:47:47 -0500
Subject: [ata] libata: ahci enclosure management bios workaround
Message-id: 20090408164747.GA5898@dhcp-210.hsv.redhat.com
O-Subject: Re: [RHEL5.4 PATCH] libata: ahci enclosure management bios workaround
Bugzilla: 488471
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Jeff Garzik <jgarzik@redhat.com>

> >During driver initialization ahci_start_port may not be
> >able to turn LEDs off because the hardware may still be
> >transmitting a message. And since the BIOS may not be
> >setting the LEDs to off the drive LEDs may end up in a
> >fault state. This has been seen on ICH9r and ICH10r when
> >configured in AHCI mode instead of RAID mode, this patch
> >doesn't key off a specific set of device IDs but will
> >give the EM transmit bit a chance to clear if busy.
> >
> >commit 4c1e9aa41b2f9afe8f26e2efe5bb4695f6c40772
> >
> >This also includes a fix to ahci_transmit_led_message
> >where the saved off led_state included the OR'd in
> >port number, this caused ahci_led_show to report an
> >incorrect value.
> >
> >commit 208f2a886a2f6cf329c9fcbf8d29a0dd245cc763
> >
> >This fixes BZ 488471, Intel and Sun have verified
> >this fix with a -137.el5 test kernel, please review and
> >ACK.
> >
> >Thanks,
> >David
> >

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index fb31aa3..0599d98 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -73,6 +73,7 @@ static ssize_t ahci_led_store(struct ata_port *ap, const char *buf,
 static ssize_t ahci_transmit_led_message(struct ata_port *ap, u32 state,
 					ssize_t size);
 #define MAX_SLOTS 8
+#define MAX_RETRY 15
 
 enum {
 	AHCI_PCI_BAR		= 5,
@@ -1073,6 +1074,8 @@ static void ahci_start_port(struct ata_port *ap)
 	struct ahci_port_priv *pp = ap->private_data;
 	struct ata_link *link;
 	struct ahci_em_priv *emp;
+	ssize_t rc;
+	int i;
 
 	/* enable FIS reception */
 	ahci_start_fis_rx(ap);
@@ -1084,7 +1087,17 @@ static void ahci_start_port(struct ata_port *ap)
 	if (ap->flags & ATA_FLAG_EM) {
 		ata_port_for_each_link(link, ap) {
 			emp = &pp->em_priv[link->pmp];
-			ahci_transmit_led_message(ap, emp->led_state, 4);
+
+			/* EM Transmit bit maybe busy during init */
+			for (i = 0; i < MAX_RETRY; i++) {
+				rc = ahci_transmit_led_message(ap,
+							       emp->led_state,
+							       4);
+				if (rc == -EBUSY)
+					udelay(100);
+				else
+					break;
+			}
 		}
 	}
 
@@ -1286,7 +1299,7 @@ static ssize_t ahci_transmit_led_message(struct ata_port *ap, u32 state,
 	em_ctl = readl(mmio + HOST_EM_CTL);
 	if (em_ctl & EM_CTL_TM) {
 		spin_unlock_irqrestore(ap->lock, flags);
-		return -EINVAL;
+		return -EBUSY;
 	}
 
 	/*
@@ -1303,7 +1316,7 @@ static ssize_t ahci_transmit_led_message(struct ata_port *ap, u32 state,
 	writel(message[1], mmio + hpriv->em_loc+4);
 
 	/* save off new led state for port/slot */
-	emp->led_state = message[1];
+	emp->led_state = state;
 
 	/*
 	 * tell hardware to transmit the message