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Subject[PATCH AUTOSEL 3.18 10/98] ahci_xgene: Fix the DMA state machine lockup for the ATA_CMD_PACKET PIO mode command.
Date
From: Suman Tripathi <stripathi@apm.com>

[ Upstream commit 1102407bb714dcebb43f385335bcb72f6b8843bc ]

This patch addresses the issue with ATA_CMD_PACKET pio mode
command for enumeration and device detection with ATAPI devices.
The X-Gene AHCI controller has an errata in which it cannot clear
the BSY bit after the PIO setup FIS. The dma state machine enters
CMFatalErrorUpdate state and locks up.

Signed-off-by: Suman Tripathi <stripathi@apm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/ata/ahci_xgene.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/ata/ahci_xgene.c b/drivers/ata/ahci_xgene.c
index 0ffd3c930bed..d33216155827 100644
--- a/drivers/ata/ahci_xgene.c
+++ b/drivers/ata/ahci_xgene.c
@@ -125,10 +125,11 @@ static int xgene_ahci_restart_engine(struct ata_port *ap)
* xgene_ahci_qc_issue - Issue commands to the device
* @qc: Command to issue
*
- * Due to Hardware errata for IDENTIFY DEVICE command, the controller cannot
- * clear the BSY bit after receiving the PIO setup FIS. This results in the dma
- * state machine goes into the CMFatalErrorUpdate state and locks up. By
- * restarting the dma engine, it removes the controller out of lock up state.
+ * Due to Hardware errata for IDENTIFY DEVICE command and PACKET
+ * command of ATAPI protocol set, the controller cannot clear the BSY bit
+ * after receiving the PIO setup FIS. This results in the DMA state machine
+ * going into the CMFatalErrorUpdate state and locks up. By restarting the
+ * DMA engine, it removes the controller out of lock up state.
*/
static unsigned int xgene_ahci_qc_issue(struct ata_queued_cmd *qc)
{
@@ -137,7 +138,8 @@ static unsigned int xgene_ahci_qc_issue(struct ata_queued_cmd *qc)
struct xgene_ahci_context *ctx = hpriv->plat_data;
int rc = 0;

- if (unlikely(ctx->last_cmd[ap->port_no] == ATA_CMD_ID_ATA))
+ if (unlikely((ctx->last_cmd[ap->port_no] == ATA_CMD_ID_ATA) ||
+ (ctx->last_cmd[ap->port_no] == ATA_CMD_PACKET)))
xgene_ahci_restart_engine(ap);

rc = ahci_qc_issue(qc);
--
2.17.1
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