Re: [lm-sensors] hwmon-vid driver from linux 2.6.29

From: Jean Delvare <khali@linux-fr.org>
To: lm-sensors@vger.kernel.org
Subject: Re: [lm-sensors] hwmon-vid driver from linux 2.6.29
Date: Mon, 08 Jun 2009 14:59:21 +0000	[thread overview]
Message-ID: <20090608165921.6e6fb5ba@hyperion.delvare> (raw)
In-Reply-To: <4A0C6BF7.9010107@assembler.cz>

On Mon, 08 Jun 2009 10:05:08 -0400, Frank Myhr wrote:
> Jean Delvare wrote:
> > You could contact the motherboard vendor and tell them about the
> > problem (the question is "Is VID5 properly routed from CPU to
> > IT8716F?") and see what they have to say about this.
> > 
> > I don't really know how to work around this. I suspect that only the
> > late 0Fh family CPUs actually make use of VID5. If I am right then we
> > could tweak the hwmon-vid VRM selection table and use 5-pin VID (VRM
> > code 24) for some of the 0Fh family CPUs. I don't know where to put the
> > limit, and this is fixing the problem where it is not... which is
> > likely to cause even more problems on other systems in the future.
> > 
> > Frank, can you please tell us for which 0Fh family CPU model you did
> > need the 6th VID pin decoding originally?
> 
> Hi Jean and others,
> 
> I'm sorry, that system is currently offline and I (not so) cleverly
> didn't back up log files so I don't have kernel-reported cpu info. But
> here is hardware spec:
> 
> cpu: AMD Athlon X2 64 4850e, ADH4850IAA5DO
> mainboard: Gigabyte GA-MA770-DS3, IT8718

Mmm, this is strange. This CPU should operate at 1.1 to 1.25 V just
like Hleb's. For this range the 5-bit VID codes are sufficient (VRM
code 24 in hwmon-vid). Thus it shouldn't have made a difference when
you added support for 6-bit VID codes. Do you remember why you wrote
that patch in the first place?

Actually I am not aware of _any_ 0Fh family CPU model running at a core
voltage below 0.9 V. This makes me wonder if we shouldn't simply map
the 0Fh family to 5-bit VID decoding and be done with it. This would
avoid potential issues such as the one Hleb is hitting (although I
don't disagree this appears to be a mainboard wiring issue in the first
place.)

Opinions?

-- 
Jean Delvare

_______________________________________________
lm-sensors mailing list
lm-sensors@lm-sensors.org
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors