libata: ahci enclosure management bios workaround

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.

Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 788bba2b1e17..6ca4bc0fcae3 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -78,6 +78,7 @@ 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,
@@ -1115,6 +1116,8 @@ 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);
@@ -1126,7 +1129,17 @@ static void ahci_start_port(struct ata_port *ap)
         if (ap->flags & ATA_FLAG_EM) {
                 ata_for_each_link(link, ap, EDGE) {
                         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;
+                        }
                 }
         }
 
@@ -1331,7 +1344,7 @@ 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;
         }
 
         /*