On 04/08/2014 11:04 AM, Lorenzo Pieralisi wrote:
ARM arch timers are tightly coupled with the CPU logic and lose context on platform implementing HW power management when cores are powered down at run-time. Marking the arch timers as C3STOP regardless of power management capabilities causes issues on platforms with no power management, since in that case the arch timers cannot possibly enter states where the timer loses context at runtime and therefore can always be used as a high resolution clockevent device. In order to fix the C3STOP issue in a way compliant with how real HW works, this patch adds a boolean property to the arch timer bindings to define if the arch timer is managed by an always-on power domain. This power domain is present on all ARM platforms to date, and manages HW that must not be turned off, whatever the state of other HW components (eg power controller). On platforms with no power management capabilities, it is the only power domain present, which encompasses and manages power supply for all HW components in the system. If the timer is powered by the always-on power domain, the always-on property must be present in the bindings which means that the timer cannot be shutdown at runtime, so it is not a C3STOP clockevent device. If the timer binding does not contain the always-on property, the timer is assumed to be power-gateable, hence it must be defined as a C3STOP clockevent device. Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> Cc: Magnus Damm <damm@xxxxxxxxxxxxx> Cc: Marc Carino <marc.ceeeee@xxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> ---
Applied as 3.15 fix. Thanks -- Daniel -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
