On 01/31/2013 03:08 AM, Igor Grinberg wrote: > 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. Yes exactly. Good point I can make that bit explicit. >> >> Signed-off-by: Jon Hunter <jon-hunter@xxxxxx> > > Apart from above, > Acked-by: Igor Grinberg <grinberg@xxxxxxxxxxxxxx> Thanks Jon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
