On Fri, Sep 16, 2016 at 06:07:36PM -0400, Alex Deucher wrote:
On Fri, Sep 16, 2016 at 5:38 PM, Lukas Wunner lukas@wunner.de wrote:
On Fri, Sep 16, 2016 at 04:42:43PM -0400, Alex Deucher wrote:
drm/amdgpu: skip suspend/resume on DRM_SWITCH_POWER_DYNAMIC_OFF drm/radeon: skip suspend/resume on DRM_SWITCH_POWER_DYNAMIC_OFFThose two are unnecessary, it can't happen that the ->suspend hook is executed with the device runtime suspended.
Since commit d14d2a8453d6 ("drm: Remove dev_pm_ops from drm_class"), DRM devices are afforded direct_complete, i.e. if the GPU is runtime suspended upon system sleep, it is left in this state. The only callbacks that are executed are the ->prepare and the ->complete hook. All the callbacks in-between, like ->suspend, are skipped.
Even if direct_complete is not afforded for some reason, the PM core will automatically runtime resume the device before executing ->suspend.
That ->suspend is skipped in the DRM_SWITCH_POWER_OFF case was done because the device is suspended behind the PM core's back if runpm=0 is set. (And it doesn't work properly because the PCI core will invalidate the saved_state during ->resume_noirq. That could be solved by returning 1 from the ->prepare hook in the DRM_SWITCH_POWER_OFF case, but that's a different story.)
(Sorry for not raising this earlier, I'm not subscribed to amd-gfx.)
Thanks for the heads up. They shouldn't hurt anything and it matches what other drivers do. If you feel strongly about it, I can revert them later.
Well, superfluous code shouldn't be included just because it doesn't hurt or because others didn't know better either, or removed because of someone else's feelings. ;-)
You can find the runtime resume before execution of the driver ->suspend callback in drivers/pci/pci-driver.c:pci_pm_suspend():
const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; ... pm_runtime_resume(dev); ... if (pm->suspend) { ... error = pm->suspend(dev);
The device is prevented from auto-suspending because of a runtime PM ref acquired beforehand in drivers/base/power/main.c:device_prepare().
Best regards,
Lukas