[PATCH AUTOSEL for 4.9 211/293] x86/tsc: Allow TSC calibration without PIT

From: Peter Zijlstra [ Upstream commit 30c7e5b123673d5e570e238dbada2fb68a87212c ] 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

[PATCH AUTOSEL for 4.9 211/293] x86/tsc: Allow TSC calibration without PIT

From: Peter Zijlstra [ Upstream commit 30c7e5b123673d5e570e238dbada2fb68a87212c ] 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