| Message ID | 20191206213936.v6.16.I699496bbaa62574e084c63564a2497fcca8fe951@changeid |
|---|---|
| State | Accepted |
| Commit | 77dd7c6854f3bd8ddc422f0cb1953071fe00dc6c |
| Delegated to: | Bin Meng |
| Headers | show |
| Series | x86: Add initial support for apollolake | expand |
On Sat, Dec 7, 2019 at 12:46 PM Simon Glass <sjg@chromium.org> wrote: > > On x86 platforms the timer is reset to 0 when the SoC is reset. Having > this as the timer base is useful since it provides an indication of how > long it takes before U-Boot is running. > > When U-Boot sets the timer base to something else, time is lost and we > no-longer have an accurate account of the time since reset. This > particularly affects bootstage. > > Change the default to not read the timer base, leaving it at 0. Add an > option for when U-Boot is the secondary bootloader. > > Signed-off-by: Simon Glass <sjg@chromium.org> > Reviewed-by: Bin Meng <bmeng.cn@gmail.com> > --- > > Changes in v6: None > Changes in v5: None > Changes in v4: > - Enable option for slimbootloader, coreboot, efi > - Reverse the sense of the CONFIG option > > Changes in v3: None > Changes in v2: None > > arch/x86/cpu/coreboot/Kconfig | 1 + > arch/x86/cpu/slimbootloader/Kconfig | 1 + > drivers/timer/Kconfig | 14 ++++++++++++++ > drivers/timer/tsc_timer.c | 3 ++- > lib/efi/Kconfig | 1 + > 5 files changed, 19 insertions(+), 1 deletion(-) > applied to u-boot-x86/next, thanks!
diff --git a/arch/x86/cpu/coreboot/Kconfig b/arch/x86/cpu/coreboot/Kconfig index 93f61f2fa4..c8e6a889d0 100644 --- a/arch/x86/cpu/coreboot/Kconfig +++ b/arch/x86/cpu/coreboot/Kconfig @@ -24,5 +24,6 @@ config SYS_COREBOOT imply CMD_CBFS imply FS_CBFS imply CBMEM_CONSOLE + imply X86_TSC_READ_BASE endif diff --git a/arch/x86/cpu/slimbootloader/Kconfig b/arch/x86/cpu/slimbootloader/Kconfig index 3ea4c9958c..58a9ca01a9 100644 --- a/arch/x86/cpu/slimbootloader/Kconfig +++ b/arch/x86/cpu/slimbootloader/Kconfig @@ -17,3 +17,4 @@ config SYS_SLIMBOOTLOADER imply USB_EHCI_HCD imply USB_XHCI_HCD imply E1000 + imply X86_TSC_READ_BASE diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig index 5f4bc6edb6..41f9755133 100644 --- a/drivers/timer/Kconfig +++ b/drivers/timer/Kconfig @@ -174,6 +174,20 @@ config X86_TSC_TIMER help Select this to enable Time-Stamp Counter (TSC) timer for x86. +config X86_TSC_READ_BASE + bool "Read the TSC timer base on start-up" + depends on X86_TSC_TIMER + help + On x86 platforms the TSC timer tick starts at the value 0 on reset. + This it makes no sense to read the timer on boot and use that as the + base, since we will miss some time taken to load U-Boot, etc. This + delay is controlled by the SoC and we cannot reduce it, but for + bootstage we want to record the time since reset as accurately as + possible. + + The only exception is when U-Boot is used as a secondary bootloader, + where this option should be enabled. + config MTK_TIMER bool "MediaTek timer support" depends on TIMER diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c index 0df551f94c..813817f467 100644 --- a/drivers/timer/tsc_timer.c +++ b/drivers/timer/tsc_timer.c @@ -397,7 +397,8 @@ static void tsc_timer_ensure_setup(bool early) { if (gd->arch.tsc_inited) return; - gd->arch.tsc_base = rdtsc(); + if (IS_ENABLED(CONFIG_X86_TSC_READ_BASE)) + gd->arch.tsc_base = rdtsc(); if (!gd->arch.clock_rate) { unsigned long fast_calibrate; diff --git a/lib/efi/Kconfig b/lib/efi/Kconfig index 919e314a0c..93b8564492 100644 --- a/lib/efi/Kconfig +++ b/lib/efi/Kconfig @@ -1,6 +1,7 @@ config EFI bool "Support running U-Boot from EFI" depends on X86 + imply X86_TSC_READ_BASE help U-Boot can be started from EFI on certain platforms. This allows EFI to perform most of the system init and then jump to U-Boot for