Messages in this thread | | | From | Guan-Yu Lin <> | Date | Mon, 26 Feb 2024 17:45:00 +0800 | Subject | Re: [PATCH v3] PM / core: conditionally skip system pm in device/driver model |
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On Sat, Feb 24, 2024 at 1:44 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Fri, Feb 23, 2024 at 3:38 PM Guan-Yu Lin <guanyulin@google.com> wrote: > > > > In systems with a main processor and a co-processor, asynchronous > > controller management can lead to conflicts. One example is the main > > processor attempting to suspend a device while the co-processor is > > actively using it. To address this, we introduce a new sysfs entry > > called "conditional_skip". This entry allows the system to selectively > > skip certain device power management state transitions. To use this > > feature, set the value in "conditional_skip" to indicate the type of > > state transition you want to avoid. Please review /Documentation/ABI/ > > testing/sysfs-devices-power for more detailed information. > > > > Signed-off-by: Guan-Yu Lin <guanyulin@google.com> > > Please explain how this is intended to work. That is, what exactly > you expect to happen when the new attribute is set.
The sysfs entry 'conditional_skip' for a device indicates which power transitions (e.g. PM_EVENT_SUSPEND) are omitted within the system power management flow. During the processing of an identified power transition, the device's power.entry will not be added to the dpm_prepared_list, preventing the device from undergoing that transition. As 'conditional_skip' is modifiable at runtime, a device's participation in system power management can be dynamically enabled or disabled.
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