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From: Juergen Beisert <juergen127@kreuzholzen.de>
To: linux-kernel@vger.kernel.org
Cc: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>,
	takada <takada@mbf.nifty.com>
Subject: Re: fix typo in geode_configre()@cyrix.c
Date: Wed, 17 Jan 2007 01:24:11 +0100	[thread overview]
Message-ID: <200701170124.11928.juergen127@kreuzholzen.de> (raw)
In-Reply-To: <20070109173348.GF17269@csclub.uwaterloo.ca>

On Tuesday 09 January 2007 18:33, Lennart Sorensen wrote:
> Then for the next one it does:
> ccr3 = GetCx86(CX86_CCR3);
> setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10);
>
> Couldn't that have been:
> setCx86(CX86_CCR3, (getCx86(CX86_CCR3) & 0x0f) | 0x10);
>
> No temp variable, and again it clearly does not intend to restore the
> value again later (even though the bug actually did cause the value to
> be restored by accident).

No, ccr3 should be restored to protect some registers (or at least bit 4 
should be cleared in ccr3).

BTW:
In function set_cx86_inc()
[...]
	/* PCR1 -- Performance Control */
	/* Incrementor on, whatever that is */
	setCx86(CX86_PCR1, getCx86(CX86_PCR1) | 0x02);
	/* PCR0 -- Performance Control */
	/* Incrementor Margin 10 */
	setCx86(CX86_PCR0, getCx86(CX86_PCR0) | 0x04);
[...]

This setting is only valid for 200MHz...266MHz CPUs, for 300MHz and 333MHz 
CPUs the Incrementor Margin should be 1-1.

There is an AppNote about this setting:
AMD Geode GX1 Processor Memory Timings for Maximum Performance.

Juergen

  parent reply	other threads:[~2007-01-17  0:24 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-09  9:41 takada
2007-01-09 15:43 ` Lennart Sorensen
2007-01-17  0:15   ` Juergen Beisert
2007-01-09 17:33 ` Lennart Sorensen
2007-01-16 16:38   ` takada
2007-01-16 16:50     ` Lennart Sorensen
2007-01-16 17:12       ` takada
2007-01-24  4:04         ` Andrew Morton
2007-01-16 22:47     ` Lennart Sorensen
2007-01-17  0:24   ` Juergen Beisert [this message]
2007-01-17 15:26   ` takada

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