[PATCH] ahci: enable GHC.AE bit before set GHC.HR

["Peer Chen" <peerchen@gmail.com>]

According to the description of section 5.2.2.1 and 10.1.2 of AHCI specification rev1_1/rev1_2, GHC.HR shall only be set to ¡®1¡¯
by software when GHC.AE is set to ¡®1¡¯.

Signed-off-by: Peer Chen <peerchen@gmail.com>
---
--- linux-2.6.23-rc7/drivers/ata/ahci.c.orig	2007-09-20 11:01:55.000000000 -0400
+++ linux-2.6.23-rc7/drivers/ata/ahci.c	2007-09-20 11:07:31.000000000 -0400
@@ -834,6 +834,10 @@ static int ahci_reset_controller(struct 
 	void __iomem *mmio = host->iomap[AHCI_PCI_BAR];
 	u32 tmp;
 
+        /* turn on AHCI mode before controller reset*/
+        writel(HOST_AHCI_EN, mmio + HOST_CTL);
+        (void) readl(mmio + HOST_CTL);  /* flush */
+
 	/* global controller reset */
 	tmp = readl(mmio + HOST_CTL);
 	if ((tmp & HOST_RESET) == 0) {
-
 				
--------------
Peer Chen
2007-09-21

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