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Commit 3e3183ba authored by David Woodhouse's avatar David Woodhouse Committed by Linus Torvalds
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[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: default avatarDavid Woodhouse <dwmw2@infradead.org>
Cc: Christer Weinigel <wingel@nano-system.com>
Cc: <Jordan.Crouse@amd.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 225add61

drivers/i2c/busses/scx200_acb.c

+5 −2
Original line number Diff line number Diff line
@@ -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",