linux-kernel - Re: [BUG 2.6.20-rc2] atkbd.c: Spurious ACK

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Date:	Sat, 30 Dec 2006 08:20:56 +0100
From:	Rene Herman <rene.herman@...il.com>
To:	Dmitry Torokhov <dtor@...ightbb.com>
CC:	Laurent Riffard <laurent.riffard@...e.fr>,
	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Vojtech Pavlik <vojtech@...e.cz>
Subject: Re: [BUG 2.6.20-rc2] atkbd.c: Spurious ACK

Dmitry Torokhov wrote:

> Somehow you get 2 ACks in a row, I wonder if on your boxes i8042
> pumps command and data into keyboard before i8042_interrupt gets a
> chance to run. Could you please apply the debug patch below and tell
> me the pattern of the data flow.

Yes, I believe the below trace confirms what you said? Both the ED and 
the 00/05 are sent before the first ACK gets back, by a 1 jiffie margin:

drivers/input/serio/i8042.c: ed -> i8042 (panic blink) [N]
drivers/input/serio/i8042.c: 05 -> i8042 (panic blink) [N + 2]
drivers/input/serio/i8042.c: fa <- i8042 (interrupt, 0, 1) [N + 3]
drivers/input/serio/i8042.c: fa <- i8042 (interrupt, 0, 1) [N + 6]
drivers/input/serio/i8042.c: ed -> i8042 (panic blink) [M]
drivers/input/serio/i8042.c: 00 -> i8042 (panic blink) [M + 2]
drivers/input/serio/i8042.c: fa <- i8042 (interrupt, 0, 1) [M + 3]
drivers/input/serio/i8042.c: fa <- i8042 (interrupt, 0, 1) [M + 6]

The +2, +3 and +6 are constant. Forgot to pay attention to M - N, but I 
suppose it's not too important.

For me, the patch as you posted it is actually good to go. No more 
spurious ACK complaints...

Thanks,
Rene.

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