NeilBrown <neilb@xxxxxxx> writes: > On Mon, 21 Jan 2013 13:38:59 +0200 Igor Grinberg <grinberg@xxxxxxxxxxxxxx> > wrote: > >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> Hi Neil, >> >> On 01/21/13 11:28, NeilBrown wrote: >> > >> > >> > The standard suspend sequence involves runtime_resuming >> > devices before suspending the system. >> > So just saving context in runtime_suspend and restoring it >> > in runtime resume isn't enough. We must also save in "suspend" >> > and restore in "resume". >> > >> > Without this patch, and OMAP3 system with off_mode enabled will find >> > the musb port non-functional after suspend/resume. With the patch it >> > works perfectly. >> >> Hmmm... Some time ago, this has been removed in >> 5d193ce8 (usb: musb: PM: fix context save/restore in suspend/resume path) >> >> Am I missing something? Or things changed and now this patch is correct? > > Hi Igor, > thanks for alerting me to that patch .... does anyone else get the feeling > that power management to too complex to be understood by a mere human? Yes. ;) > That commit (5d193ce8) suggests that the musb-hdrc device is an > 'omap_device', or maybe has a PM domain set to something else. > However it isn't/doesn't. dev->pm_domain is NULL. So no PM domain layer > will ever call the musb_core musb_runtime_suspend/resume. > > The parent device - musb-omap2430 - is an omap device, does have pm_domain > set, and does have its omap2430_runtime_suspend/resume called for system > suspend and so the context for that device is saved and restored. > However that doesn't help the context for musb-hdrc. > > Whether musb ever was an omap_device is beyond my archaeological skills to > determine. > > Kevin: Was musb-hdrc ever a device with a pm_domain? or was it only ever > the various possible parents that had domains? > Are you able to defend your earlier patch in today's kernel? It > certainly causes my device not to work properly. Sorry for the delay here, I'm back to a place where I can test this on real hardware. My patch was fixing a real hang when musb was built-in (or loaded), in host-mode (mini-A cable attached) but no devices attached. I just tried to reproduce this, and with your patch, the system hangs during suspend. That being said, your description makes sense why this context save/restore is needed. Perhaps your patch needs to add a check whether the device is runtime suspended (I gather this is what Ruslan's patch is doing.) Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
