Date: Mon, 17 Dec 2007 22:28:27 +0100
From: Ingo Molnar <mingo@elte.hu>
To: "David P. Reed" <dpreed@reed.com>
Cc: Rene Herman <rene.herman@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>,
       Paul Rolland <rol@as2917.net>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Pavel Machek <pavel@ucw.cz>, Thomas Gleixner <tglx@linutronix.de>,
       linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
       rol@witbe.net
Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override.
Message-ID: <20071217212827.GB22828@elte.hu>
References: <476524DB.7020806@gmail.com> <20071216152250.GA21245@elte.hu> <4765D43E.1010800@gmail.com> <20071217105744.GA14315@elte.hu> <4766684D.40202@gmail.com> <20071217130933.GB27992@elte.hu> <47667812.8050708@gmail.com> <47667A85.3080100@reed.com> <20071217143900.GA16604@elte.hu> <4766D035.7090104@reed.com>
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* David P. Reed <dpreed@reed.com> wrote:

> Ingo -
>
> I finished testing the rolled up patch that you provided.  It seems to work 
> just fine.  Thank you for putting this all together and persevering in this 
> long and complex discussion. 
> Here are the results, on the offending laptop, using 2.6.24-rc5 plus that 
> one patch.
>
> First: booted with normal boot parameters (no io_delay=):
>
>    According to dmesg, 0xed is used.
>
>    hwclock ran fine, hundreds of times.
>    my shell script loop doing "cat /dev/nvram > /dev/null" ran fine, 
> several times.
>    Running Rene's "port 80" speed test ran fine once, then froze the system 
> hard.  (expected)
>
> Second: booted with io_delay=0x80, several tests, rebooting after freezes:
>
>    hwclock froze system hard.  (this is the problem that drove me to find 
> this bug).
>    my shell script loop froze system hard.
>
> Third: booted with io_delay=none:
>
>    hwclock ran fine, also hundreds of times.
>    my shell script loop ran fine several times.
>    Running rene's port80 test ran fine twice, froze system hard on third 
> try.
>
> Fourth: booted with io_delay=udelay:
>
>    hwclock ran fine, also hundreds of times.
>    my shell script loop ran fine several times.
>    Running Rene's port80 test ran fine, froze system hard on second try.
>
> Analysis:
>
>    patch works fine, and default to 0xed seems super conservative. I 
> will probably use the boot parameter io_delay=none, because I don't 
> seem to have any I/O
>    devices that require any delays - and this way I can find any that 
>    do.

great, and thanks for the extensive testing! I've added this line to the 
patch:

 Tested-by: "David P. Reed" <dpreed@reed.com>

if you dont mind.

	Ingo
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