The patch titled
SCX200_ACB: eliminate spurious timeout errors.
has been added to the -mm tree. Its filename is
scx200_acbeliminate-spurious-timeout-errors.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: SCX200_ACB: eliminate spurious timeout errors.
From: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
While busy-waiting for completion, check the hardware after scheduling;
don't schedule and then immediately check the _timeout_. If the yield()
took a long time (as it does on my OLPC prototype board when it's busy),
we'd report a timeout even though the hardware was now ready.
This fixes it, and also switches the yield() for a cond_resched() because
we don't actually want to be _that_ nice about it. I see nice
tightly-packed SMBus transactions now, rather than waiting for milliseconds
between successive phases.
Actually, we shouldn't be busy-waiting here at all. We should be using
interrupts. That's an exercise for another day though.
Signed-off-by: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Christer Weinigel <wingel@xxxxxxxxxxxxxxx>
Cc: <Jordan.Crouse@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/i2c/busses/scx200_acb.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff -puN drivers/i2c/busses/scx200_acb.c~scx200_acbeliminate-spurious-timeout-errors drivers/i2c/busses/scx200_acb.c
--- a/drivers/i2c/busses/scx200_acb.c~scx200_acbeliminate-spurious-timeout-errors
+++ a/drivers/i2c/busses/scx200_acb.c
@@ -232,7 +232,7 @@ static void scx200_acb_poll(struct scx20
unsigned long timeout;
timeout = jiffies + POLL_TIMEOUT;
- while (time_before(jiffies, timeout)) {
+ while (1) {
status = inb(ACBST);
/* Reset the status register to avoid the hang */
@@ -242,7 +242,10 @@ static void scx200_acb_poll(struct scx20
scx200_acb_machine(iface, status);
return;
}
- yield();
+ if (time_after(jiffies, timeout))
+ break;
+ cpu_relax();
+ cond_resched();
}
dev_err(&iface->adapter.dev, "timeout in state %s\n",
_
Patches currently in -mm which might be from dwmw2@xxxxxxxxxxxxx are
scx200_acbeliminate-spurious-timeout-errors.patch
git-gfs2.patch
git-mtd.patch
mtd-maps-ixp4xx-partition-parsing.patch
fix-the-unlock-addr-lookup-bug-in-mtd-jedec-probe.patch
fs-conversions-from-kmallocmemset-to-kzcalloc.patch
headers_check-improve-include-regexp.patch
headers_check-clarify-error-message.patch
the-scheduled-removal-of-some-oss-drivers-fix-fix.patch
debug-shared-irqs.patch
debug-shared-irqs-kconfig-fix.patch
-
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