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authorTejun Heo <htejun@gmail.com>2007-07-16 14:29:40 +0900
committerJeff Garzik <jeff@garzik.org>2007-07-20 08:19:05 -0400
commit008a78961ec72990d09d7625ef9499d7317d040d (patch)
treeaa356bbd961b7425017a3037fec509ffb761d332
parentbadc2341579511a247f5993865aa68379e283c5c (diff)
libata: improve SATA PHY speed down logic
sata_down_spd_limit() first reads the current SPD from SStatus and limit the speed to the lower one of one below the current limit or one below the current SPD in SStatus. SPD may not be accessible or valid when SPD down is requested making sata_down_spd_limit() fail when it's most needed. This patch makes the current SPD cached after each successful reset and forces GEN I speed (1.5Gbps) if neither of SStatus or the cached value is valid, so sata_down_spd_limit() is now guaranteed to lower the speed limit if lower speed is available. Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
-rw-r--r--drivers/ata/libata-core.c29
-rw-r--r--drivers/ata/libata-eh.c6
-rw-r--r--include/linux/libata.h1
3 files changed, 29 insertions, 7 deletions
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 5718c247e23..c325b7a4246 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2389,21 +2389,35 @@ int sata_down_spd_limit(struct ata_port *ap)
u32 sstatus, spd, mask;
int rc, highbit;
+ if (!sata_scr_valid(ap))
+ return -EOPNOTSUPP;
+
+ /* If SCR can be read, use it to determine the current SPD.
+ * If not, use cached value in ap->sata_spd.
+ */
rc = sata_scr_read(ap, SCR_STATUS, &sstatus);
- if (rc)
- return rc;
+ if (rc == 0)
+ spd = (sstatus >> 4) & 0xf;
+ else
+ spd = ap->sata_spd;
mask = ap->sata_spd_limit;
if (mask <= 1)
return -EINVAL;
+
+ /* unconditionally mask off the highest bit */
highbit = fls(mask) - 1;
mask &= ~(1 << highbit);
- spd = (sstatus >> 4) & 0xf;
- if (spd <= 1)
- return -EINVAL;
- spd--;
- mask &= (1 << spd) - 1;
+ /* Mask off all speeds higher than or equal to the current
+ * one. Force 1.5Gbps if current SPD is not available.
+ */
+ if (spd > 1)
+ mask &= (1 << (spd - 1)) - 1;
+ else
+ mask &= 1;
+
+ /* were we already at the bottom? */
if (!mask)
return -EINVAL;
@@ -5995,6 +6009,7 @@ void ata_dev_init(struct ata_device *dev)
/* SATA spd limit is bound to the first device */
ap->sata_spd_limit = ap->hw_sata_spd_limit;
+ ap->sata_spd = 0;
/* High bits of dev->flags are used to record warm plug
* requests which occur asynchronously. Synchronize using
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 19f9947bd96..183eaf466d4 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1799,12 +1799,18 @@ static int ata_eh_reset(struct ata_port *ap, int classify,
}
if (rc == 0) {
+ u32 sstatus;
+
/* After the reset, the device state is PIO 0 and the
* controller state is undefined. Record the mode.
*/
for (i = 0; i < ATA_MAX_DEVICES; i++)
ap->device[i].pio_mode = XFER_PIO_0;
+ /* record current link speed */
+ if (sata_scr_read(ap, SCR_STATUS, &sstatus) == 0)
+ ap->sata_spd = (sstatus >> 4) & 0xf;
+
if (postreset)
postreset(ap, classes);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index c732b3e78e2..16ebdf152c7 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -531,6 +531,7 @@ struct ata_port {
unsigned int cbl; /* cable type; ATA_CBL_xxx */
unsigned int hw_sata_spd_limit;
unsigned int sata_spd_limit; /* SATA PHY speed limit */
+ unsigned int sata_spd; /* current SATA PHY speed */
/* record runtime error info, protected by host lock */
struct ata_eh_info eh_info;