Hi Laurent On Sun, Dec 25, 2011 at 3:08 PM, Laurent Pinchart <[email protected]> wrote: >> > I'm not sure how this clock stuff works, but I'm guessing the device >> > is supposed to go to sleep at some points in time, and with your patch >> > "OMAP3/4: iommu: adapt to runtime pm" it won't, as long as the module >> > is loaded, unless I'm missing something. >> >> The device should be able to be put to sleep at anytime when it is NOT >> being used. AFAIK there is no mechanism for the main processor (the >> one running the kernel) to know when the other iommus are not being >> used, given that they are in independent processors/subsystems, at >> least for the ones in the DSP or M3 processors. Once the user releases >> its iommu resource it means it is no longer using it, at that point >> the device can be put to sleep. > > How should the OMAP3 ISP driver proceed to make sure that its IOMMU is clocked > off when it doesn't need it ?
If there is an specific scenario where the iommu should be disabled, iommu_detach_device can be called to release the iommu resource. On suspend/resume scenarios runtime pm callbacks should still be able to put the device in idle. Regards, Omar -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
