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Date: Fri, 04 May 2007 20:42:43 -0400
From: Jeff Garzik <jeff@...zik.org>
To: Michael Chan <mchan@...adcom.com>
CC: davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH 10/11][TG3]: Reduce spurious interrupts.
Michael Chan wrote:
> [TG3]: Reduce spurious interrupts.
>
> Spurious interrupts are often encountered especially on systems
> using the 8259 PIC mode. This is because the I/O write to deassert
> the interrupt is posted and won't get to the chip immediately. As
> a result, the IRQ may remain asserted after the IRQ handler exits,
> causing spurious interrupts.
>
> An unconditional read to flush the I/O write to force the IRQ to de-
> assert immediately is not desirable because it impacts performance in
> the fast path. So we only do this after we have some indications of
> spurious interrupts.
>
> Signed-off-by: Michael Chan <mchan@...adcom.com>
hmmmm, this is a bit questionable that it needs to be here.
I think it's just a fact of life that it is important to flush certain
writes...
I'm not sure a driver needs to be adding code to avoid the obvious
solution. It would be annoying if all drivers had code to do this.
Jeff
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