From: Jeff Garzik <jeff@garzik.org>
Date: Wed, 26 Sep 2007 04:02:41 +0000 (-0400)
Subject: [libata] AHCI: enable AHCI mode, before using AHCI reset
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=3cc3eb1148e4b2dfabf7a1dcf36fd8be1331ca95;p=deliverable%2Flinux.git

[libata] AHCI: enable AHCI mode, before using AHCI reset

AHCI spec says host-reset bit may only be set when the ahci-enable bit
is also set.

Noticed by Peer Chen <peerchen@gmail.com>

Signed-off-by: Jeff Garzik <jeff@garzik.org>
---

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 9f3c591c7214..b615390b6b8a 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -827,8 +827,14 @@ static int ahci_reset_controller(struct ata_host *host)
 	void __iomem *mmio = host->iomap[AHCI_PCI_BAR];
 	u32 tmp;
 
-	/* global controller reset */
+	/* we must be in AHCI mode, before using anything
+	 * AHCI-specific, such as HOST_RESET.
+	 */
 	tmp = readl(mmio + HOST_CTL);
+	if (!(tmp & HOST_AHCI_EN))
+		writel(tmp | HOST_AHCI_EN, mmio + HOST_CTL);
+
+	/* global controller reset */
 	if ((tmp & HOST_RESET) == 0) {
 		writel(tmp | HOST_RESET, mmio + HOST_CTL);
 		readl(mmio + HOST_CTL); /* flush */