Hi Omar, On Thursday 05 January 2012 20:24:25 Ramirez Luna, Omar wrote: > On Sun, Dec 25, 2011 at 3:08 PM, Laurent Pinchart 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. Runtime PM might indeed be a better option. The OMAP3 ISP doesn't need to IOMMU until video streams are started, so we should keep it powered down in that case. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
