On 2017-03-21 13:19, tip-bot for Lu Baolu wrote: > Commit-ID: dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b > Gitweb: http://git.kernel.org/tip/dd759d93f4dd4fd2f345a78ad1223bb3edf3ee7b > Author: Lu Baolu <[email protected]> > AuthorDate: Tue, 21 Mar 2017 16:01:29 +0800 > Committer: Ingo Molnar <[email protected]> > CommitDate: Tue, 21 Mar 2017 12:28:45 +0100 > > x86/timers: Add simple udelay calibration > > Add a simple udelay calibration in x86 architecture-specific > boot-time initializations. This will get a workable estimate > for loops_per_jiffy. Hence, udelay() could be used after this > initialization. > > Signed-off-by: Lu Baolu <[email protected]> > Acked-by: Thomas Gleixner <[email protected]> > Cc: Andy Lutomirski <[email protected]> > Cc: Borislav Petkov <[email protected]> > Cc: Brian Gerst <[email protected]> > Cc: Denys Vlasenko <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Cc: H. Peter Anvin <[email protected]> > Cc: Josh Poimboeuf <[email protected]> > Cc: Linus Torvalds <[email protected]> > Cc: Mathias Nyman <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: [email protected] > Link: > http://lkml.kernel.org/r/[email protected] > Signed-off-by: Ingo Molnar <[email protected]> > --- > arch/x86/kernel/setup.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 4bf0c89..e70204e 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -837,6 +837,26 @@ dump_kernel_offset(struct notifier_block *self, unsigned > long v, void *p) > return 0; > } > > +static void __init simple_udelay_calibration(void) > +{ > + unsigned int tsc_khz, cpu_khz; > + unsigned long lpj; > + > + if (!boot_cpu_has(X86_FEATURE_TSC)) > + return; > + > + cpu_khz = x86_platform.calibrate_cpu(); > + tsc_khz = x86_platform.calibrate_tsc(); > + > + tsc_khz = tsc_khz ? : cpu_khz; > + if (!tsc_khz) > + return; > + > + lpj = tsc_khz * 1000; > + do_div(lpj, HZ); > + loops_per_jiffy = lpj; > +} > + > /* > * Determine if we were loaded by an EFI loader. If so, then we have also > been > * passed the efi memmap, systab, etc., so we should use these data > structures > @@ -985,6 +1005,8 @@ void __init setup_arch(char **cmdline_p) > */ > x86_configure_nx(); > > + simple_udelay_calibration(); > + > parse_early_param(); > > #ifdef CONFIG_MEMORY_HOTPLUG >
Can we move this past init_hypervisor_platform()? Otherwise, the x86_platform hooks aren't fully initialized yet, and we may use the wrong functions. Jan -- Siemens AG, Corporate Technology, CT RDA ITP SES-DE Corporate Competence Center Embedded Linux
