* Peter Ujfalusi <peter.ujfalusi@xxxxxx> [160128 01:01]: > On 01/27/2016 05:54 PM, Tony Lindgren wrote: > > * Peter Ujfalusi <peter.ujfalusi@xxxxxx> [160127 01:12]: > >> The dynamic or on demand pm_runtime does not work correctly on am335x and > >> am437x due to interference with hwmod. > > > > Hmm care expand a bit what is the problem with this "interference"? > > The idea was to enable/power on only the TPTCs which is actually in use and > leave the unused ones off. Which is is nice and all, but... > The original implementation did the pm_runtime calls for the tptcs from the > edma tpcc driver instance and the main issue was that I did the pm_runtime > calls in the edma-tpcc pm callbacks as well. > Since omap hwmod/device also handles pm_runtime on behalf of the drivers we > got nasty issues, kernel crash, warnings on suspend/resume. > > Then I did implemented the on demand power management in a totally different > way, still keeping only tptcs enabled which is in use. > In this way all the omap hwmod/device incoherency was gone and things looked > fine, but it turned out that on second suspend we are not able to wake up the > board. > I and Tero debugged this a bit and it turns out that we need to kepp all tptcs > enabled and powered, otherwise the HW will not going to be able to complete > the transition, breaking suspend/resume. Probably you only need to keep the tptcs being used enabled though? They should be completely independent otherwise? > With pm_runtime_enable() + get_sync() on all tptcs we can suspend and resume > w/o problems and they will be disabled/enabled by omap hwmod/device code, > following nicely the power state of the system. > > As a note: I did tried the suspend/resume with the old code with dra7, but it > turned out that on dra7 SW has no control over the tptc power state, it > follows the system in HW. > > In short: The implementation was flawed and even if the implementation is > correct the HW will lock up if we do on demand tptc power management. OK interesting. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
