Searched hist:"30 c7e5b123673d5e570e238dbada2fb68a87212c" (Results 1 – 2 of 2) sorted by relevance
| /openbmc/linux/arch/x86/include/asm/ |
| H A D | i8259.h | diff 30c7e5b123673d5e570e238dbada2fb68a87212c Fri Dec 22 03:20:11 CST 2017 Peter Zijlstra <peterz@infradead.org> x86/tsc: Allow TSC calibration without PIT
Zhang Rui reported that a Surface Pro 4 will fail to boot with
lapic=notscdeadline. Part of the problem is that that machine doesn't have
a PIT.
If, for some reason, the TSC init has to fall back to TSC calibration, it
relies on the PIT to be present.
Allow TSC calibration to reliably fall back to HPET.
The below results in an accurate TSC measurement when forced on a IVB:
tsc: Unable to calibrate against PIT
tsc: No reference (HPET/PMTIMER) available
tsc: Unable to calibrate against PIT
tsc: using HPET reference calibration
tsc: Detected 2792.451 MHz processor
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: len.brown@intel.com
Cc: rui.zhang@intel.com
Link: https://lkml.kernel.org/r/20171222092243.333145937@infradead.org
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| /openbmc/linux/arch/x86/kernel/ |
| H A D | tsc.c | diff 30c7e5b123673d5e570e238dbada2fb68a87212c Fri Dec 22 03:20:11 CST 2017 Peter Zijlstra <peterz@infradead.org> x86/tsc: Allow TSC calibration without PIT
Zhang Rui reported that a Surface Pro 4 will fail to boot with
lapic=notscdeadline. Part of the problem is that that machine doesn't have
a PIT.
If, for some reason, the TSC init has to fall back to TSC calibration, it
relies on the PIT to be present.
Allow TSC calibration to reliably fall back to HPET.
The below results in an accurate TSC measurement when forced on a IVB:
tsc: Unable to calibrate against PIT
tsc: No reference (HPET/PMTIMER) available
tsc: Unable to calibrate against PIT
tsc: using HPET reference calibration
tsc: Detected 2792.451 MHz processor
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: len.brown@intel.com
Cc: rui.zhang@intel.com
Link: https://lkml.kernel.org/r/20171222092243.333145937@infradead.org
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