Hi, On Tuesday, September 11, 2012, Dave Airlie wrote: > Hi Rafael, > > I've been investigating runtime PM support for some use-cases on GPUs. > > In some laptops we have a secondary GPU (optimus) that can be powered > up for certain 3D tasks and then turned off when finished with. Now I > did an initial pass on supporting it without using the kernel runtime > PM stuff, but Alan said I should take a look so here I am. Alan Stern or Alan Cox? :-) > While I've started to get a handle on things, we have a bit of an > extra that I'm not sure we cater for. > > Currently we get called from the PCI layer which after we are finished > with our runtime suspend callback, will go put the device into the > correct state etc, however on these optimus/powerxpress laptops we > have a separate ACPI or platform driver controlled power switch that > we need to call once the PCI layer is finished the job. This switch > effectively turns the power to the card completely off leaving it > drawing no power. > > No we can't hit the switch from the driver callback as the PCI layer > will get lost, so I'm wondering how you'd envisage we could plug this > in. Hmm. In principle we might modify pci_pm_runtime_suspend() so that it doesn't call pci_finish_runtime_suspend() if pci_dev->state_saved is set. That would actually make it work in analogy with pci_pm_suspend_noirq(), so perhaps it's not even too dangerous. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
