[PATCH 5/5] ARM: OMAP3: Update clocksource timer selection
From: Igor Grinberg <hidden>
Date: 2013-01-31 09:08:35
Also in:
linux-omap
On 01/30/13 19:04, Jon Hunter wrote:
When booting with device-tree for OMAP3 and AM335x devices and a gptimer is used as the clocksource (which is always the case for AM335x), a gptimer located in a power domain that is not always-on is selected. Ideally we should use a gptimer located in a power domain that is always on (such as the wake-up domain) so that time can be maintained during a kernel suspend without keeping on additional power domains unnecessarily. In order to fix this so that we can select a gptimer located in a power domain that is always-on, the following changes were made ... 1. Currently, only when selecting a gptimer to use for a clockevent timer, do we pass a timer property that can be used to select a specific gptimer. Change this so that we can pass a property when selecting a gptimer to use for a clocksource timer too. 2. Currently, when selecting either a gptimer to use for a clockevent timer or a clocksource timer and no timer property is passed, then the first available timer is selected regardless of the properties it has. Change this so that if no properties are passed, then a timer that does not have additional features (such as always-on, dsp-irq, pwm, and secure) is selected. Please note that using a gptimer for both clocksource and clockevents can have a system power impact during idle. The reason being is that OMAP and AMxxx devices typically only have one gptimer in a power domain that is always-on. Therefore when the kernel is idle both the clocksource and clockevent timers will be active and this will keep additional power domains on. During kernel suspend, only the clocksource timer is active and therefore, it is better to use a gptimer in a power domain that is always-on for clocksource.
This should explain the gptimer number switch in the #if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX) section below, right? I would really like to see that clearly stated in the commit message. For instance: ... it is better to use a gptimer in a power domain that is always-on for clocksource. Therefore we switch to use the first gptimer for clocksource and the second for clockevents.
Signed-off-by: Jon Hunter <redacted>
Apart from above, Acked-by: Igor Grinberg <redacted>
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--- arch/arm/mach-omap2/timer.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-)diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c index af20be7..acf9f82 100644 --- a/arch/arm/mach-omap2/timer.c +++ b/arch/arm/mach-omap2/timer.c
[...]
quoted hunk ↗ jump to hunk
@@ -557,19 +567,19 @@ void __init omap##name##_sync32k_timer_init(void) \ #if defined(CONFIG_ARCH_OMAP2) || defined(CONFIG_ARCH_OMAP4) || \ defined(CONFIG_SOC_OMAP5) OMAP_SYS_32K_TIMER_INIT(2, 1, "timer_32k_ck", "ti,timer-alwon", - 2, "timer_sys_ck"); + 2, "timer_sys_ck", NULL); #endif #ifdef CONFIG_ARCH_OMAP3 OMAP_SYS_32K_TIMER_INIT(3, 1, "timer_32k_ck", "ti,timer-alwon", - 2, "timer_sys_ck"); + 2, "timer_sys_ck", NULL); OMAP_SYS_32K_TIMER_INIT(3_secure, 12, "secure_32k_fck", "ti,timer-secure", - 2, "timer_sys_ck"); + 2, "timer_sys_ck", NULL); #endif /* CONFIG_ARCH_OMAP3 */ #if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX) -OMAP_SYS_GP_TIMER_INIT(3, 1, "timer_sys_ck", "ti,timer-alwon", - 2, "timer_sys_ck"); +OMAP_SYS_GP_TIMER_INIT(3, 2, "timer_sys_ck", NULL, + 1, "timer_sys_ck", "ti,timer-alwon"); #endif #ifdef CONFIG_ARCH_OMAP4
-- Regards, Igor.