linux-kernel - [PATCH] x86: provide a DMI based port 0x80 I/O delay override.

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Date:	Mon, 17 Dec 2007 22:33:57 +0100
From:	Rene Herman <rene.herman@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>
CC:	Rene Herman <rene.herman@...il.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Ingo Molnar <mingo@...e.hu>, "David P. Reed" <dpreed@...d.com>,
	Paul Rolland <rol@...917.net>, Pavel Machek <pavel@....cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, rol@...be.net
Subject: [PATCH] x86: provide a DMI based port 0x80 I/O delay override.

On 17-12-07 21:57, H. Peter Anvin wrote:

> Rene Herman wrote:
>> On 17-12-07 17:12, Alan Cox wrote:
>>
>>> I don't think we should be offering udelay based delays at this point.
>>> There are a lot of drivers to fix first. This is just one trivial 
>>> example
>>
>> I agree. This thread's too full of people calling this outb method a 
>> dumb hack. It's a well-known legacy PC thing and while in practice the 
>> udelay might be a functional replacement for a majority of cases (save 
>> the races you are finding) a delay proportional to the bus speed makes 
>> great sense certainly when talking to hardware that itself runs 
>> proportinal to the bus speed for example.
>>
>> So, really, how about just sticking in this minimal version for now? 
>> Only switches the port to 0xed based on DMI and is all that is needed 
>> to fix the actual problem. This should be minimal and no-risk enough 
>> that it could also go to .24 if people want it to. It'll fix a few HP 
>> laptops (I'll try and get/verify the dv6000z DMI strings as well).
>>
> 
> I think retaining the command-line option available is a good thing, 
> though.  If nothing else, it is something very quick we can ask other 
> people to try if they seem to have similar problems.

Well, yes, I guess that does make sense. It's back again. Named the choices 
"standard" and "alternate" again as I feel "0x80" and "0xed" suggest they're 
free values a bit too much but if anyone feels strongly about it, so be it.

> Other than that, this alternate-port patch is a low-impact patch not 
> affecting hardware not on the blacklist, which makes it appropriate for 
> 2.6.24 IMO.

Signed-off-by: Rene Herman <rene.herman@...il.com>

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