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 ? -- balbi
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