| Message ID | 1501038725-20850-6-git-send-email-bmeng.cn@gmail.com |
|---|---|
| State | Accepted |
| Commit | 167a40166bb116a19d23c946b6394636da34f3cf |
| Delegated to: | Bin Meng |
| Headers | show |
On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote: > Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr(), as that > better describes what the routine does. > > This keeps in sync with Linux kernel commit: > 02c0cd2: x86/tsc_msr: Remove irqoff around MSR-based TSC enumeration > > Signed-off-by: Bin Meng <bmeng.cn@gmail.com> > --- > > drivers/timer/tsc_timer.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > Reviewed-by: Simon Glass <sjg@chromium.org>
On Tue, Aug 1, 2017 at 5:11 PM, Simon Glass <sjg@chromium.org> wrote: > On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote: >> Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr(), as that >> better describes what the routine does. >> >> This keeps in sync with Linux kernel commit: >> 02c0cd2: x86/tsc_msr: Remove irqoff around MSR-based TSC enumeration >> >> Signed-off-by: Bin Meng <bmeng.cn@gmail.com> >> --- >> >> drivers/timer/tsc_timer.c | 13 +++++++++---- >> 1 file changed, 9 insertions(+), 4 deletions(-) >> > > Reviewed-by: Simon Glass <sjg@chromium.org> applied to u-boot-x86, thanks!
diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c index b242e74..4d1fc9c 100644 --- a/drivers/timer/tsc_timer.c +++ b/drivers/timer/tsc_timer.c @@ -71,11 +71,16 @@ static int match_cpu(u8 family, u8 model) (freq_desc_tables[cpu_index].freqs[freq_id]) /* - * Do MSR calibration only for known/supported CPUs. + * TSC on Intel Atom SoCs capable of determining TSC frequency by MSR is + * reliable and the frequency is known (provided by HW). * - * Returns the calibration value or 0 if MSR calibration failed. + * On these platforms PIT/HPET is generally not available so calibration won't + * work at all and there is no other clocksource to act as a watchdog for the + * TSC, so we have no other choice than to trust it. + * + * Returns the TSC frequency in MHz or 0 if HW does not provide it. */ -static unsigned long __maybe_unused try_msr_calibrate_tsc(void) +static unsigned long __maybe_unused cpu_mhz_from_msr(void) { u32 lo, hi, ratio, freq_id, freq; unsigned long res; @@ -336,7 +341,7 @@ static int tsc_timer_probe(struct udevice *dev) if (!uc_priv->clock_rate) { unsigned long fast_calibrate; - fast_calibrate = try_msr_calibrate_tsc(); + fast_calibrate = cpu_mhz_from_msr(); if (!fast_calibrate) { fast_calibrate = quick_pit_calibrate(); if (!fast_calibrate)
Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr(), as that better describes what the routine does. This keeps in sync with Linux kernel commit: 02c0cd2: x86/tsc_msr: Remove irqoff around MSR-based TSC enumeration Signed-off-by: Bin Meng <bmeng.cn@gmail.com> --- drivers/timer/tsc_timer.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)