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From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: daniel.lezcano@linaro.org, tglx@linutronix.de
Cc: linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	linux-doc@vger.kernel.org
Subject: [PATCH 92/92] clocksource/drivers/arm_arch_timer: Control the evtstrm via the cmdline
Date: Tue, 28 Jun 2016 12:51:50 +0200	[thread overview]
Message-ID: <1467111111-12587-17-git-send-email-daniel.lezcano@linaro.org> (raw)
In-Reply-To: <1467111111-12587-1-git-send-email-daniel.lezcano@linaro.org>

From: Will Deacon <will.deacon@arm.com>

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>
---
 Documentation/kernel-parameters.txt  |  8 ++++++++
 drivers/clocksource/Kconfig          | 12 +++++++-----
 drivers/clocksource/arm_arch_timer.c | 10 +++++++++-
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 82b42c9..2c92f1d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -687,6 +687,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			[SPARC64] tick
 			[X86-64] hpet,tsc
 
+	clocksource.arm_arch_timer.evtstrm=
+			[ARM,ARM64]
+			Format: <bool>
+			Enable/disable the eventstream feature of the ARM
+			architected timer so that code using WFE-based polling
+			loops can be debugged more effectively on production
+			systems.
+
 	clearcpuid=BITNUM [X86]
 			Disable CPUID feature X for the kernel. See
 			arch/x86/include/asm/cpufeatures.h for the valid bit
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 7acdf3d..5677886 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 9e33309..5effd30 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;
-- 
1.9.1

  parent reply	other threads:[~2016-06-28 10:54 UTC|newest]

Thread overview: 153+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <577251A4.7030508@linaro.org>
2016-06-28 10:30 ` [PATCH 01/92] clocksource/drivers/armada-370-xp: Make syscore_ops static Daniel Lezcano
2016-06-28 10:30   ` [PATCH 02/92] clocksource/drivers/digicolor: Fix warning of non-static function Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 03/92] clocksource/drivers/samsung_pwm_timer: Fix endian accessors Daniel Lezcano
2016-06-28 10:30   ` [PATCH 04/92] clocksource/drivers/samsung_pwm: Fix typo in Kconfig Daniel Lezcano
2016-06-28 10:30   ` [PATCH 05/92] dt-bindings: Document rk3399 rk-timer bindings Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 06/92] clocksource/drivers/rockchip: Add the dynamic irq flag to the timer Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 07/92] clocksource/drivers/rockchip: Add support for the rk3399 SoC Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 08/92] arm64: dts: rockchip: Add rktimer device node for rk3399 Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 09/92] clocksource/drivers/oxnas-rps: Add Oxford Semiconductor RPS Dual Timer Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 10/92] dt-bindings: clocksource: Add Oxford Semiconductor RPS Timer bindings Daniel Lezcano
2016-06-28 10:30   ` [PATCH 11/92] of: Add a new macro to declare_of for one parameter function returning a value Daniel Lezcano
2016-06-28 10:30   ` [PATCH 12/92] clocksource/drivers/clksrc-probe: Introduce init functions with return code Daniel Lezcano
2016-06-28 10:30   ` [PATCH 13/92] clocksource/drivers/rockchip_timer: Convert init function to return error Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 14/92] clocksource/drivers/mtk_timer: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 15/92] clocksource/drivers/exynos_mct: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 16/92] clocksource/drivers/asm9260: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 17/92] clocksource/drivers/cadence_ttc: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 18/92] clocksource/drivers/st_lpc: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 19/92] clocksource/drivers/dw_apb_timer: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 20/92] clocksource/drivers/clps711x: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 21/92] clocksource/drivers/digicolor: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 22/92] clocksource/drivers/armv7m_systick: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 23/92] clocksource/drivers/bcm2835_timer: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 24/92] clocksource/drivers/bcm_kona: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 25/92] clocksource/drivers/clksrc-dbx500: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 26/92] clocksource/drivers/fsl_ftm_timer: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 27/92] clocksource/drivers/arm_arch_timer: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 28/92] clocksource/drivers/arm_global_timer: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 29/92] clocksource/drivers/h8300_timer16: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 30/92] clocksource/drivers/h8300_timer8: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 31/92] clocksource/drivers/h8300_tpu: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 32/92] clocksource/drivers/meson6_timer.c: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 33/92] clocksource/drivers/mips-gic-timer: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 34/92] clocksource/drivers/moxart: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 35/92] clocksource/drivers/mps2-timer: " Daniel Lezcano
2016-06-28 10:30     ` Daniel Lezcano
2016-06-28 10:30   ` [PATCH 36/92] clocksource/drivers/mxs: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 37/92] clocksource/drivers/nomadik-mtu: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 38/92] clocksource/drivers/pxa: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 39/92] clocksource/drivers/qcom: " Daniel Lezcano
2016-06-28 10:30   ` [PATCH 40/92] clocksource/drivers/samsung_pwm: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 41/92] clocksource/drivers/sun4i: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 42/92] clocksource/drivers/tango_xtal: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 43/92] clocksource/drivers/tegra20: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 44/92] clocksource/drivers/time-armada-370-xp: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 45/92] clocksource/drivers/time-efm32: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 46/92] clocksource/drivers/time-lpc32xx: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 47/92] clocksource/drivers/orion: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 48/92] clocksource/drivers/pistachio: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 49/92] clocksource/drivers/atlas7: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 50/92] clocksource/drivers/atmel-pit: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 51/92] clocksource/drivers/atmel-st: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 52/92] clocksource/drivers/prima2: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 53/92] clocksource/drivers/imx-gpt: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 54/92] clocksource/drivers/integrator-ap: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 55/92] clocksource/drivers/keystone: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 56/92] clocksource/drivers/sp804: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 57/92] clocksource/drivers/stm32: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 58/92] clocksource/drivers/sun5i: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 59/92] clocksource/drivers/ti-32k: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 60/92] clocksource/drivers/u300: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 61/92] clocksource/drivers/versatile: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 62/92] clocksource/drivers/vf_pit_timer: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 63/92] clocksource/drivers/vt8500: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 64/92] clocksource/drivers/zevio: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 65/92] clocksource/drivers/microblaze: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 66/92] clocksource/drivers/ralink: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 67/92] clocksource/drivers/nios2: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 68/92] clocksource/drivers/smp_twd: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 69/92] clocksource/drivers/nps: " Daniel Lezcano
2016-06-28 10:31   ` [PATCH 70/92] clocksource/drivers/arc: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 71/92] clocksource/drivers/oxnas-rps: " Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
     [not found]   ` <1467109911-11060-1-git-send-email-daniel.lezcano-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2016-06-28 10:31     ` [PATCH 72/92] clocksources: Switch back to the clksrc table Daniel Lezcano
2016-06-28 10:31       ` Daniel Lezcano
2016-06-28 10:31       ` Daniel Lezcano
2016-06-28 10:31       ` Daniel Lezcano
2016-06-28 10:31       ` Daniel Lezcano
2016-06-28 10:31   ` [PATCH 73/92] clk: Add missing clk_get_sys() stub Daniel Lezcano
2016-06-28 10:31   ` [PATCH 74/92] clocksource/drivers/bcm_kona: Remove useless header <asm/mach/time.h> Daniel Lezcano
2016-06-29  5:53     ` Ray Jui
2016-06-28 10:31   ` [PATCH 75/92] clocksource/drivers/bcm2835: Add the COMPILE_TEST option Daniel Lezcano
2016-06-28 10:31     ` Daniel Lezcano
2016-06-28 10:51 ` [PATCH 76/92] clocksource/drivers/armv7m_systick: " Daniel Lezcano
2016-06-28 10:51   ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 77/92] clocksource/drivers/bcm_kona: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 78/92] clocksource/drivers/clps_711x: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 79/92] clocksource/drivers/atlas7: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 80/92] clocksource/drivers/moxart: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 81/92] clocksource/drivers/mxs: Remove useless header <asm/mach/time.h> Daniel Lezcano
2016-06-28 10:51   ` [PATCH 82/92] clocksource/drivers/mxs: Add the COMPILE_TEST option Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 83/92] clocksource/drivers/prima2: Remove useless header <asm/mach/time.h> Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 84/92] clocksource/drivers/prima2: Add the COMPILE_TEST option Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 85/92] clocksource/drivers/u300: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 86/92] clocksource/drivers/nspire: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 87/92] clocksource/drivers/keystone: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 88/92] clocksource/drivers/integrator-ap: " Daniel Lezcano
2016-06-28 10:51     ` Daniel Lezcano
2016-06-28 10:51   ` [PATCH 89/92] clocksource/drivers/arm_global_timer: " Daniel Lezcano
2016-06-28 10:51   ` [PATCH 90/92] clocksource/drivers/timer-atmel-st: " Daniel Lezcano
2016-06-28 10:51   ` [PATCH 91/92] clocksource/drivers/versatile: " Daniel Lezcano
2016-06-28 10:51   ` Daniel Lezcano [this message]
2016-07-06 10:24 ` [PULL] : clockevents for 4.8 Daniel Lezcano
2016-07-06 10:44   ` Thomas Gleixner
2016-07-06 10:47     ` Thomas Gleixner
2016-07-06 13:21       ` Daniel Lezcano

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