• Nishanth Menon's avatar
    PM / QoS: Add debugfs support to view the list of constraints · f5f4eda4
    Nishanth Menon authored
    PM QoS requests are notoriously hard to debug and made even
    more so due to their highly dynamic nature. Having visibility
    into the internal data representation per constraint allows
    us to have much better appreciation of potential issues or
    bad usage by drivers in the system.
    
    So introduce for all classes of PM QoS, an entry in
    /sys/kernel/debug/pm_qos that shall show all the current
    requests as well as the snapshot of the value these requests
    boil down to. For example:
    ==> /sys/kernel/debug/pm_qos/cpu_dma_latency <==
    1: 4444: Active
    2: 2000000000: Default
    3: 2000000000: Default
    4: 2000000000: Default
    Type=Minimum, Value=4444, Requests: active=1 / total=4
    
    ==> /sys/kernel/debug/pm_qos/memory_bandwidth <==
    Empty!
    
    ...
    
    The actual value listed will have their meaning based
    on the QoS it is on, the 'Type' indicates what logic
    it would use to collate the information - Minimum,
    Maximum, or Sum. Value is the collation of all requests.
    This interface also compares the values with the defaults
    for the QoS class and marks the ones that are
    currently active.
    Signed-off-by: default avatarNishanth Menon <nm@ti.com>
    Signed-off-by: default avatarDave Gerlach <d-gerlach@ti.com>
    Acked-by: default avatarKevin Hilman <khilman@linaro.org>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    f5f4eda4
qos.c 19.1 KB