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authorRobert Hancock <hancockr@shaw.ca>2007-03-22 12:39:04 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2007-04-06 03:43:11 -0700
commit83b72f1c7cc4bfdb0958a2c1709c5a17ea10c7dd (patch)
tree9cfd40fb99ff7cb63ca0bfb9b5b1d4f2c4bffc67
parent9f6a92b47b7580d35170712933f4eaab63d72238 (diff)
downloadlinux-linaro-stable-83b72f1c7cc4bfdb0958a2c1709c5a17ea10c7dd.tar.gz
sata_nv: delay on switching between NCQ and non-NCQ commands
sata_nv: delay on switching between NCQ and non-NCQ commands This patch appears to solve some problems with commands timing out in cases where an NCQ command is immediately followed by a non-NCQ command (or possibly vice versa). This is a rather ugly solution, but until we know more about why this is needed, this is about all we can do. [backport to 2.6.20 by Chuck Ebbert <cebbert@redhat.com>] Signed-off-by: Robert Hancock <hancockr@shaw.ca> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: Jeff Garzik <jeff@garzik.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/ata/sata_nv.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index f7a963eb1f02..91f24b1a2dc3 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -214,6 +214,7 @@ struct nv_adma_port_priv {
struct nv_adma_prd *aprd;
dma_addr_t aprd_dma;
u8 flags;
+ int last_issue_ncq;
};
#define NV_ADMA_CHECK_INTR(GCTL, PORT) ((GCTL) & ( 1 << (19 + (12 * (PORT)))))
@@ -1151,6 +1152,7 @@ static unsigned int nv_adma_qc_issue(struct ata_queued_cmd *qc)
{
struct nv_adma_port_priv *pp = qc->ap->private_data;
void __iomem *mmio = nv_adma_ctl_block(qc->ap);
+ int curr_ncq = (qc->tf.protocol == ATA_PROT_NCQ);
VPRINTK("ENTER\n");
@@ -1166,6 +1168,14 @@ static unsigned int nv_adma_qc_issue(struct ata_queued_cmd *qc)
/* write append register, command tag in lower 8 bits
and (number of cpbs to append -1) in top 8 bits */
wmb();
+
+ if(curr_ncq != pp->last_issue_ncq) {
+ /* Seems to need some delay before switching between NCQ and non-NCQ
+ commands, else we get command timeouts and such. */
+ udelay(20);
+ pp->last_issue_ncq = curr_ncq;
+ }
+
writew(qc->tag, mmio + NV_ADMA_APPEND);
DPRINTK("Issued tag %u\n",qc->tag);