diff options
| author | Will Deacon <will.deacon@arm.com> | 2016-06-27 17:30:13 +0100 |
|---|---|---|
| committer | Daniel Lezcano <daniel.lezcano@linaro.org> | 2016-06-28 11:35:50 +0200 |
| commit | 46fd5c6b3059462131caa4d52691c9c5666c3223 (patch) | |
| tree | 244b0ef16720d6d715d3b312ef009085ea8b09b3 /drivers/clocksource | |
| parent | 5cc87a4df5009c1cbe9e087ad16c0bacdae06809 (diff) | |
| download | linux-46fd5c6b3059462131caa4d52691c9c5666c3223.tar.bz2 | |
clocksource/drivers/arm_arch_timer: Control the evtstrm via the cmdline
Disabling the eventstream can be useful for both remotely debugging a
deployed production system and development of code using WFE-based
polling loops. Whilst this can currently be controlled via a Kconfig
option (CONFIG_ARM_ARCH_TIMER_EVTSTREAM), it's often desirable to toggle
the feature on the command line, so this patch adds a new command-line
option ("clocksource.arm_arch_timer.evtstrm") to do just that. The
default behaviour is determined based on CONFIG_ARM_ARCH_TIMER_EVTSTREAM.
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/clocksource/arm_arch_timer.c | 10 |
2 files changed, 16 insertions, 6 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 7acdf3d735ac..567788664723 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -288,14 +288,16 @@ config ARM_ARCH_TIMER select CLKSRC_ACPI if ACPI config ARM_ARCH_TIMER_EVTSTREAM - bool "Support for ARM architected timer event stream generation" + bool "Enable ARM architected timer event stream generation by default" default y if ARM_ARCH_TIMER depends on ARM_ARCH_TIMER help - This option enables support for event stream generation based on - the ARM architected timer. It is used for waking up CPUs executing - the wfe instruction at a frequency represented as a power-of-2 - divisor of the clock rate. + This option enables support by default for event stream generation + based on the ARM architected timer. It is used for waking up CPUs + executing the wfe instruction at a frequency represented as a + power-of-2 divisor of the clock rate. The behaviour can also be + overridden on the command line using the + clocksource.arm_arch_timer.evtstream parameter. The main use of the event stream is wfe-based timeouts of userspace locking implementations. It might also be useful for imposing timeout on wfe to safeguard against any programming errors in case an expected diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 9e33309ad2ea..5effd3027319 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -79,6 +79,14 @@ static enum ppi_nr arch_timer_uses_ppi = VIRT_PPI; static bool arch_timer_c3stop; static bool arch_timer_mem_use_virtual; +static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM); + +static int __init early_evtstrm_cfg(char *buf) +{ + return strtobool(buf, &evtstrm_enable); +} +early_param("clocksource.arm_arch_timer.evtstrm", early_evtstrm_cfg); + /* * Architected system timer support. */ @@ -372,7 +380,7 @@ static int arch_timer_setup(struct clock_event_device *clk) enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0); arch_counter_set_user_access(); - if (IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM)) + if (evtstrm_enable) arch_timer_configure_evtstream(); return 0; |