Currently we read the tsc radio like this:
ratio = (MSR_PLATFORM_INFO >> 8) & 0x1f;
Thus we get bit 8-12 of MSR_PLATFORM_INFO, however according to the Intel manual, the ratio bits are bit 8-15.
Fix this problem by masking 0xff instead.
This keeps in sync with Linux kernel commit: 886123f: x86/tsc: Read all ratio bits from MSR_PLATFORM_INFO
Signed-off-by: Bin Meng bmeng.cn@gmail.com ---
drivers/timer/tsc_timer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c index 5c4ec00..ffbc709 100644 --- a/drivers/timer/tsc_timer.c +++ b/drivers/timer/tsc_timer.c @@ -92,7 +92,7 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
if (freq_desc_tables[cpu_index].msr_plat) { rdmsr(MSR_PLATFORM_INFO, lo, hi); - ratio = (lo >> 8) & 0x1f; + ratio = (lo >> 8) & 0xff; } else { rdmsr(MSR_IA32_PERF_STATUS, lo, hi); ratio = (hi >> 8) & 0x1f;