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authorMark Lord <liml@rtr.ca>2009-04-06 15:26:24 -0400
committerJeff Garzik <jgarzik@redhat.com>2009-04-06 20:14:10 -0400
commit12f3b6d7551306c00cf834540a33184de67c9187 (patch)
treea5de4682a13cf4d1640c15d13a7dccf9890319fa /drivers/ata
parentba68460b8e019dfd9c73ab69f5ed163a8b24e296 (diff)
downloadop-kernel-dev-12f3b6d7551306c00cf834540a33184de67c9187.zip
op-kernel-dev-12f3b6d7551306c00cf834540a33184de67c9187.tar.gz
sata_mv: workaround errata SATA#13
Add remainder of workaround for errata SATA#13. This prevents writes of certain adjacent 32-bit registers from being combined into single 64-bit writes, which might fail for the affected registers. Most of sata_mv is already safe from this issue, but adding this code to mv_write_cached_reg() will catch the remaining cases and hopefully prevent future ones. Signed-off-by: Mark Lord <mlord@pobox.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Diffstat (limited to 'drivers/ata')
-rw-r--r--drivers/ata/sata_mv.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 55d3ce0..82d928a 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -919,8 +919,26 @@ static void mv_save_cached_regs(struct ata_port *ap)
static inline void mv_write_cached_reg(void __iomem *addr, u32 *old, u32 new)
{
if (new != *old) {
+ unsigned long laddr;
*old = new;
- writel(new, addr);
+ /*
+ * Workaround for 88SX60x1-B2 FEr SATA#13:
+ * Read-after-write is needed to prevent generating 64-bit
+ * write cycles on the PCI bus for SATA interface registers
+ * at offsets ending in 0x4 or 0xc.
+ *
+ * Looks like a lot of fuss, but it avoids an unnecessary
+ * +1 usec read-after-write delay for unaffected registers.
+ */
+ laddr = (long)addr & 0xffff;
+ if (laddr >= 0x300 && laddr <= 0x33c) {
+ laddr &= 0x000f;
+ if (laddr == 0x4 || laddr == 0xc) {
+ writelfl(new, addr); /* read after write */
+ return;
+ }
+ }
+ writel(new, addr); /* unaffected by the errata */
}
}
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