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ahci_xgene: Fix the DMA state machine lockup for the ATA_CMD_PACKET PIO mode command. 

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>
This commit is contained in:
Suman Tripathi 2014-12-29 08:52:47 +05:30 committed by Tejun Heo
parent 5c0b8e0de7
commit 1102407bb7
1 changed files with 7 additions and 5 deletions
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12
drivers/ata/ahci_xgene.c
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@ -125,10 +125,11 @@ static int xgene_ahci_restart_engine(struct ata_port *ap)
* xgene_ahci_qc_issue - Issue commands to the device * xgene_ahci_qc_issue - Issue commands to the device
* @qc: Command to issue * @qc: Command to issue
* *
* Due to Hardware errata for IDENTIFY DEVICE command, the controller cannot * Due to Hardware errata for IDENTIFY DEVICE command and PACKET
* clear the BSY bit after receiving the PIO setup FIS. This results in the dma * command of ATAPI protocol set, the controller cannot clear the BSY bit
* state machine goes into the CMFatalErrorUpdate state and locks up. By * after receiving the PIO setup FIS. This results in the DMA state machine
* restarting the dma engine, it removes the controller out of lock up state. * 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) 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; struct xgene_ahci_context *ctx = hpriv->plat_data;
int rc = 0; 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); xgene_ahci_restart_engine(ap);
rc = ahci_qc_issue(qc); rc = ahci_qc_issue(qc);