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 additional
check, specific controller will fail without this.
Signed-off-by: Jian Peng <jipeng2005@xxxxxxxxx>
---
drivers/ata/libahci.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 26d4523..39e0698 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -539,6 +539,12 @@ void ahci_start_engine(struct ata_port *ap)
{
void __iomem *port_mmio = ahci_port_base(ap);
u32 tmp;
+ u8 status = readl(port_mmio + PORT_TFDATA) & 0xFF;
+
+ if (status & (ATA_BUSY | ATA_DRQ) ||
+ ahci_scr_read(&ap->link, SCR_STATUS, &tmp) ||
+ (tmp & 0x0f) != 0x03)
+ return;
/* start DMA */
tmp = readl(port_mmio + PORT_CMD);
--
1.7.4.1
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