Magnus Damm <magnus.damm@xxxxxxxxx> writes: > PM: Runtime platform device power management > > [PATCH 01/04] Driver Core: Add platform device arch data > [PATCH 02/04] Driver Core: Add idle and wakeup functions > [PATCH 03/04] PM: Add platform bus runtime dev_pm_ops > [PATCH 04/04] sh: Runtime platform device PM mockup > > These patches extend platform device and driver interfaces to > allow architectures to implement platform device runtime pm. > > Upstream runtime power management needs to be improved to fully > make use of hardware power saving features found on embedded > platforms and in common SoCs. > > For runtime power management we today have cpuidle, the clock > framework and qos. This allows the cpu core to enter various > forms of deep sleep, and for devices we may stop clocks to save > power. Modern SoCs however allow disabling of power to parts of > the chip, and we have no upstream interface to handle that today. > > I propose adding the following simple platform device functions: > - platform_device_wakeup() > - platform_device_idle() > > The idle function is used by the platform driver to let the > architecture power management code know that from now on the > device is in idle state. When the device is marked as idle > the architecture specific runtime power management may decide > to do various levels of device power management, ranging from > stopping clocks to turning off power. The dev_pm_ops callbacks > may be invoked by the runtime pm code to save and restore state > whenever the device is marked as idle. > > The wakeup function is used by the platform driver to notify the > architecture code that the driver wants to make use of the hardware > device. If the device has been put in sleep then it needs to be > woken up. This wakeup call may invoke dev_pm_ops callbacks. > > Have a look at the last patch for a SuperH mockup that shows how > it all fits together. We need this or a similar interface to be able > to enter deep sleep states on SuperH. I believe other architectures > have similar requirements. > > Signed-off-by: Magnus Damm <damm@xxxxxxxxxx> Speaking on behalf of OMAP PM developers, and as maintainer of the current OMAP PM infrastructure, this is a major step towards a generic runtime PM that we would use on OMAP as well. In the PM branch of the linux-omap tree, we currently have an ad-hoc but working infrastructure for all of this, including device-specific save/restore hooks for supporting some or all of the on-chip powerdomains to go off during idle. However, our current approach hides most of the details behind the clock framework, custom save/restore hooks and in some cases custom platform hooks passed using platform_data. I like this proposed approach much better as it generalizes the approach and allows us to share the infrastructure across arches as well as decouple device idleness from clock management. Kevin _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
