linux-kernel - Re: [PATCH] pci-quirks: HP hides SMBus controller in Compaq nx9500 laptops

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Message-ID: <20090106084121.GA9347@atrey.karlin.mff.cuni.cz>
Date:	Tue, 6 Jan 2009 09:41:21 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	Micha? Miros?aw <mirq-linux@...e.qmqm.pl>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH] pci-quirks: HP hides SMBus controller in Compaq nx9500 laptops

> On Mon, Jan 05, 2009 at 11:19:20AM -0800, Jesse Barnes wrote:
> > On Wednesday, December 31, 1969 10:46 pm Pavel Machek wrote:
> > > On Tue 2008-12-23 22:54:07, Micha? Miros?aw wrote:
> > > > I found no references to SMBus in ACPI DSDT disassembly on my laptop
> > > > so this should be safe.
> > > >
> > > > Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> > > Well, it could still be used by smm bios traps...
> > Also, the changelog doesn't include a description of what this patch fixes, if 
> > anything.  Care to resend with an explanation Michal?
> 
> This patch enables SMBus controller on HP Compaq nx9500 laptop and
> allowes to read SPD EEPROMs of the memory modules.
> I found no references to SMBus in ACPI DSDT disassembly on my laptop, but
> there are some additional devices on the bus (besides SPD chips).
> 
> rechot ~ # lspci -s 00:1f.3
> 00:1f.3 SMBus: Intel Corporation 82801EB/ER (ICH5/ICH5R) SMBus Controller (rev 02)
> 
> rechot ~ # i2cdetect -a 0
> WARNING! This program can confuse your I2C bus, cause data loss and worse!
> I will probe file /dev/i2c-0.
> I will probe address range 0x00-0x7f.
> Continue? [Y/n] y
>           0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
>      00: -- -- -- -- -- -- -- -- 08 -- -- -- -- -- -- --
>      10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>      20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>      30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>      40: -- -- -- -- 44 -- -- -- -- -- -- -- -- -- -- --
>      50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
>      60: -- -- -- -- -- -- -- -- -- 69 -- -- -- -- -- --
>      70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> 
> I observed no ill effects after scanning the bus, but YMMV.
> 
> Using the bus is probably not a good idea if the SMM code is really using
> it, and so it might be better if this patch lies in the archives for now.
> After I get the BIOS flashing to work I'll look into this.

I'm not saying SMM code _does_ use it... I just don't know, and
reading DSDT will not tell me (or you).
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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