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authorJian Peng <jipeng2005@gmail.com>2011-04-22 23:58:10 -0700
committerJeff Garzik <jgarzik@pobox.com>2011-04-24 11:35:40 -0400
commit270dac35c26433d06a89150c51e75ca0181ca7e4 (patch)
tree187f95b21867318d77b768e1e8be27b0894c239b
parent792d37af35386466cf5dda51d6b710fa1dd9aad1 (diff)
downloadlinux-270dac35c26433d06a89150c51e75ca0181ca7e4.tar.gz
libata: ahci_start_engine compliant to AHCI spec
At the end of section 10.1 of AHCI spec (rev 1.3), it states Software shall not set PxCMD.ST to 1 until it is determined that a functoinal device is present on the port as determined by PxTFD.STS.BSY=0, PxTFD.STS.DRQ=0 and PxSSTS.DET=3h Even though most AHCI host controller works without this check, specific controller will fail under this condition. Signed-off-by: Jian Peng <jipeng2005@gmail.com> Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
-rw-r--r--drivers/ata/libahci.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index d38c40fe4dd..ff9d832a163 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -561,6 +561,27 @@ void ahci_start_engine(struct ata_port *ap)
{
void __iomem *port_mmio = ahci_port_base(ap);
u32 tmp;
+ u8 status;
+
+ status = readl(port_mmio + PORT_TFDATA) & 0xFF;
+
+ /*
+ * At end of section 10.1 of AHCI spec (rev 1.3), it states
+ * Software shall not set PxCMD.ST to 1 until it is determined
+ * that a functoinal device is present on the port as determined by
+ * PxTFD.STS.BSY=0, PxTFD.STS.DRQ=0 and PxSSTS.DET=3h
+ *
+ * Even though most AHCI host controllers work without this check,
+ * specific controller will fail under this condition
+ */
+ if (status & (ATA_BUSY | ATA_DRQ))
+ return;
+ else {
+ ahci_scr_read(&ap->link, SCR_STATUS, &tmp);
+
+ if ((tmp & 0xf) != 0x3)
+ return;
+ }
/* start DMA */
tmp = readl(port_mmio + PORT_CMD);