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| author | cinap_lenrek <cinap_lenrek@gmx.de> | 2013-06-22 00:47:24 +0200 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@gmx.de> | 2013-06-22 00:47:24 +0200 |
| commit | 3487653524efc9c79e7173407446f6b83f8de81b (patch) | |
| tree | 5921900d6ca7e94e31e1572ed63c09a1a7e41b15 | |
| parent | a59b0bd6a8542337a88a16f7fb675d3cd4cbb942 (diff) | |
| download | plan9front-3487653524efc9c79e7173407446f6b83f8de81b.tar.xz | |
apic: fix lapic timer divider (fixes wrong lapic frequency on boot)
loading the divider before programming one shot mode *sometimes*
gives the wrong frequency. (X200s got 192Mhz vs. 266Mhz, after
5 boot attempts)
also reload the divider after programming periodic mode. (from
http://wiki.osdev.org/APIC_timer)
| -rw-r--r-- | sys/src/9/pc/apic.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/sys/src/9/pc/apic.c b/sys/src/9/pc/apic.c index eada39531..4e006e8fb 100644 --- a/sys/src/9/pc/apic.c +++ b/sys/src/9/pc/apic.c @@ -124,6 +124,12 @@ lapiconline(void) lapicw(LapicTICR, lapictimer.max); lapicw(LapicTIMER, LapicCLKIN|LapicPERIODIC|(VectorPIC+IrqTIMER)); + /* + * not strickly neccesary, but reported (osdev.org) to be + * required for some machines. + */ + lapicw(LapicTDCR, lapictdxtab[lapictimer.tdx]); + lapicw(LapicTPR, 0); } @@ -134,8 +140,8 @@ static void lapictimerinit(void) { Retry: - lapicw(LapicTDCR, lapictdxtab[lapictimer.tdx]); lapicw(LapicTIMER, ApicIMASK|LapicCLKIN|LapicONESHOT|(VectorPIC+IrqTIMER)); + lapicw(LapicTDCR, lapictdxtab[lapictimer.tdx]); if(lapictimer.hz == 0ULL){ uvlong x, v, hz; |