• Chanwoo Choi's avatar
    PM / devfreq: Add support delayed timer for polling mode · 4dc3bab8
    Chanwoo Choi authored
    Until now, the devfreq driver using polling mode like simple_ondemand
    governor have used only deferrable timer for reducing the redundant
    power consumption. It reduces the CPU wake-up from idle due to polling mode
    which check the status of Non-CPU device.
    
    But, it has a problem for Non-CPU device like DMC device with DMA operation.
    Some Non-CPU device need to do monitor continuously regardless of CPU state
    in order to decide the proper next status of Non-CPU device.
    
    So, add support the delayed timer for polling mode to support
    the repetitive monitoring. The devfreq driver and user can select
    the kind of timer on either deferrable and delayed timer.
    
    For example, change the timer type of DMC device
    based on Exynos5422-based Odroid-XU3 as following:
    
    - If want to use deferrable timer as following:
    echo deferrable > /sys/class/devfreq/10c20000.memory-controller/timer
    
    - If want to use delayed timer as following:
    echo delayed > /sys/class/devfreq/10c20000.memory-controller/timer
    Reviewed-by: default avatarBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
    Reviewed-by: default avatarLukasz Luba <lukasz.luba@arm.com>
    Signed-off-by: default avatarChanwoo Choi <cw00.choi@samsung.com>
    4dc3bab8
sysfs-class-devfreq 4.52 KB