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-rw-r--r--drivers/ata/ahci.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 9f3c591c721..b615390b6b8 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 */