On Tue, 23 Apr 2013, Vivek Gautam wrote: > >> Alright, so here's my understanding: > >> > >> I suggested letting e.g. DWC3 enable the PHY's runtime_pm; Alan said > >> that it could be done before that so that DWC3 sees an enabled PHY > >> during probe. > > > > Basically right. Help me to understand the overall situation a little > > better: > > > > What code registers the PHY initially? > PHY is added to global list by PHY drivers (like > phy-samsung-usb2.c/phy-omap-usb2.c) > by usb_add_phy() API Then this routine should initialize the PHY. The initialized state could be either active or suspended, your choice. Suspended would be best, in case the PHY never gets used. > > What routine does the DWC3 driver call to register itself > > as a consumer of the PHY? > I think DWC3 doesn't registers itself as consumer of PHY, > rather it gets that PHY from > the list using devm_usb_get_phy()/devm_usb_get_phy_by_phandle() API. > DWC3 can now call PHY's initialization sequence using usb_phy_init(). > So, before DWC3 initializes the PHY, PHYs should be in active state. Then usb_phy_init should make sure the PHY is in the active state. If usb_add_phy() left the PHY suspended, then this routine should call pm_runtime_get_sync(). After DWC3 (or any other driver) has acquired the PHY, it can call pm_runtime_put/get() however it likes, so long as the calls balance properly. If the driver isn't runtime-PM aware then it won't use any of these calls, and the PHY will remain active the entire time. > > Likewise, what routine does it call to unregister itself? > Once DWC3's remove() is called PHYs are put. Is there a routine analogous to usb_phy_init() that gets called when PHY is released? That routine would do the opposite of usb_phy_init(), putting the PHY back into its initialized state. Alan Stern -- 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
