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x86: GEODE add the "mfgptfix" boot time option to fix MFGPT timers 

The new "mfgptfix" boot command line option may be usd to fix MFGPT
timers on AMD Geode platforms when the BIOS has incorrectly applied
a workaround. TinyBIOS version 0.98 is known to be affected, 0.99
fixes the problem by letting the user disable the workaround.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Willy Tarreau 2008-01-30 13:33:33 +01:00 committed by Ingo Molnar
parent 45078cb5e2
commit e6c4dc6c36
2 changed files with 20 additions and 0 deletions
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5
Documentation/kernel-parameters.txt
View File

@ -1092,6 +1092,11 @@ and is between 256 and 4096 characters. It is defined in the file
Multi-Function General Purpose Timers on AMD Geode
platforms.
mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
the BIOS has incorrectly applied a workaround. TinyBIOS
version 0.98 is known to be affected, 0.99 fixes the
problem by letting the user disable the workaround.
mga= [HW,DRM]
mousedev.tap_time=

15
arch/x86/kernel/mfgpt_32.c
View File

@ -63,6 +63,21 @@ static int __init mfgpt_disable(char *s)
}
__setup("nomfgpt", mfgpt_disable);
/* Reset the MFGPT timers. This is required by some broken BIOSes which already
* do the same and leave the system in an unstable state. TinyBIOS 0.98 is
* affected at least (0.99 is OK with MFGPT workaround left to off).
*/
static int __init mfgpt_fix(char *s)
{
u32 val, dummy;
/* The following udocumented bit resets the MFGPT timers */
val = 0xFF; dummy = 0;
wrmsr(0x5140002B, val, dummy);
return 1;
}
__setup("mfgptfix", mfgpt_fix);
/*
* Check whether any MFGPTs are available for the kernel to use. In most
* cases, firmware that uses AMD's VSA code will claim all timers during