Hi Bin, On 3 January 2015 at 07:40, Bin Meng <bmeng...@gmail.com> wrote: > By default U-Boot automatically calibrates TSC running frequency via > MSR and PIT. The calibration may not work on every x86 processor, so > a new Kconfig option CONFIG_TSC_CALIBRATION_BYPASS is introduced to > allow bypassing the calibration and assign a hardcoded TSC frequency > CONFIG_TSC_FREQ_IN_MHZ. > > Normally the bypass should be turned on in a simulation environment > like qemu. > > Signed-off-by: Bin Meng <bmeng...@gmail.com>
Acked-by: Simon Glass <s...@chromium.org> But see my optional thoughts below. > --- > > arch/x86/Kconfig | 18 ++++++++++++++++++ > arch/x86/lib/tsc_timer.c | 8 ++++++-- > 2 files changed, 24 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index ebf72b3..9c11f0e 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -317,6 +317,24 @@ config FRAMEBUFFER_VESA_MODE > > endmenu > > +config TSC_CALIBRATION_BYPASS > + bool "Bypass TSC calibration" > + default n > + help > + By default U-Boot automatically calibrates TSC running frequency via > + MSR and PIT. If the calibration does not work on your board, select > + this option and provide a hardcoded TSC running frequency below. Do you think TSC, MSR and PIT should be spelled out in the help? I worry that people won't make much sense of this. For example, if PIT is Platform Independent Timer we could save 'Platform Independent Timer (PIT)'. > + > + Normally this option should be turned on in a simulation environment > + like qemu. > + > +config TSC_FREQ_IN_MHZ > + int "TSC running frequency in MHz" > + depends on TSC_CALIBRATION_BYPASS > + default 1000 > + help > + The running frequency in MHz of TSC > + > source "arch/x86/cpu/ivybridge/Kconfig" > > source "arch/x86/cpu/queensbay/Kconfig" > diff --git a/arch/x86/lib/tsc_timer.c b/arch/x86/lib/tsc_timer.c > index fb9afed..7f5ba2c 100644 > --- a/arch/x86/lib/tsc_timer.c > +++ b/arch/x86/lib/tsc_timer.c > @@ -78,7 +78,7 @@ static int match_cpu(u8 family, u8 model) > * > * Returns the calibration value or 0 if MSR calibration failed. > */ > -static unsigned long try_msr_calibrate_tsc(void) > +static unsigned long __maybe_unused try_msr_calibrate_tsc(void) > { > u32 lo, hi, ratio, freq_id, freq; > unsigned long res; > @@ -199,7 +199,7 @@ static inline int pit_expect_msb(unsigned char val, u64 > *tscp, > #define MAX_QUICK_PIT_MS 50 > #define MAX_QUICK_PIT_ITERATIONS (MAX_QUICK_PIT_MS * PIT_TICK_RATE / 1000 / > 256) > > -static unsigned long quick_pit_calibrate(void) > +static unsigned long __maybe_unused quick_pit_calibrate(void) > { > int i; > u64 tsc, delta; > @@ -306,6 +306,9 @@ unsigned __attribute__((no_instrument_function)) long > get_tbclk_mhz(void) > if (gd->arch.tsc_mhz) > return gd->arch.tsc_mhz; > > +#ifdef CONFIG_TSC_CALIBRATION_BYPASS > + fast_calibrate = CONFIG_TSC_FREQ_IN_MHZ; > +#else > fast_calibrate = try_msr_calibrate_tsc(); > if (!fast_calibrate) { > > @@ -313,6 +316,7 @@ unsigned __attribute__((no_instrument_function)) long > get_tbclk_mhz(void) > if (!fast_calibrate) > panic("TSC frequency is ZERO"); > } > +#endif > > gd->arch.tsc_mhz = fast_calibrate; > return fast_calibrate; > -- > 1.8.2.1 > Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot