Hi, On Thu, Apr 4, 2013 at 12:48 PM, Felipe Balbi <balbi@xxxxxx> wrote: > Hi, > > On Wed, Apr 03, 2013 at 02:14:02PM -0400, Alan Stern wrote: >> > > Lets suppose DWC3 enables runtime_pm on USB 2 type phy, >> > > it will try to go into suspend state and thereby call runtime_suspend(), if any. >> > > And PHY will come to active state only when its consumer wakes it up, >> > > and this consumer is operational >> > > only when its related PHY is in fully functional state. >> > > So do we have a situation in which this PHY goes into low power state >> > > in its runtime_suspend(), >> > > resulting in non-detection of devices on further attach (since PHY is >> > > in low power state) ? >> > > >> > > Will the controller (like EHCI/OHCI) be functional now ? >> > >> > ehci/ohci need to cope with that by calling usb_phy_autopm_get_sync(), >> > right ? (so does DWC3 :-) >> >> Maybe you guys have already got this all figured out -- if so, feel >> free to ignore this email. >> >> Some subsystems handle this issue by calling pm_runtime_get_sync() >> before probing a driver and pm_runtime_put_sync() after unbinding the >> driver. If the driver is runtime-PM-enabled, it then does its own >> put_sync near the end of its probe routine and get_sync in its release >> routine. > > sounds a bit 'fishy' to me... So a separate entity would call > pm_runtime_get_sync(), even when we don't have registered dev_pm_ops, > then drivers need to check if runtime_pm is enabled and call > pm_runtime_put*() conditionally before returning from probe(). One > remove, we might have another issue: device is already runtime_suspended > (due to e.g. autosuspend) when module is removed, a call to > pm_runtime_put_sync() will be unbalanced. No ? May be i am misinterpreting !! If PHYs are runtime-PM enabled (PHY probe calls *runtime_enable*), then the consumers need to call pm_runtime_get_sync whever they want to access PHY. Besides PHYs also need to *put_sync* just before their probe is finishing, so that it's availbale for autosuspend. I, however didn't understand the need of PHY to *get_sync* itself in release routine. -- Thanks & Regards Vivek -- 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
