diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/mfgpt_32.c | 15 |
2 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index fe3031d5643..5d171b7b839 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -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= diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c index 3960ab7e149..219f86eb612 100644 --- a/arch/x86/kernel/mfgpt_32.c +++ b/arch/x86/kernel/mfgpt_32.c @@ -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 |