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

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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 Multi-Function General Purpose Timers on AMD Geode
platforms. 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] mga= [HW,DRM]
mousedev.tap_time= 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); __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 * 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 * cases, firmware that uses AMD's VSA code will claim all timers during