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authorDavid Woodhouse <dwmw2@infradead.org>2006-08-05 12:15:19 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-08-06 08:57:49 -0700
commit3e3183bab0257a6d02038658c53b491e1378612f (patch)
tree35221f1808e85674d9ba0ff93ce0cc4bce7edf7f
parent225add619624b4877941470f31d297e0151b21be (diff)
downloadlinux-2.6.34-ux500-3e3183bab0257a6d02038658c53b491e1378612f.tar.gz
[PATCH] SCX200_ACB: eliminate spurious timeout errors
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@infradead.org> Cc: Christer Weinigel <wingel@nano-system.com> Cc: <Jordan.Crouse@amd.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/i2c/busses/scx200_acb.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/i2c/busses/scx200_acb.c b/drivers/i2c/busses/scx200_acb.c
index ced309ff056..eae9e81be37 100644
--- a/drivers/i2c/busses/scx200_acb.c
+++ b/drivers/i2c/busses/scx200_acb.c
@@ -232,7 +232,7 @@ static void scx200_acb_poll(struct scx200_acb_iface *iface)
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 scx200_acb_iface *iface)
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",