Changes in v3 - Added a dt property 'snps,allow-rtsusp-on-u3' to make this feature platform dependent as per the feedback from Thinh N. - Changed the RT idle/suspend/resume handling to device mode specific and dt property dependent. - Modified the cover letter to document how resume is handled on qcom platforms. Changes in v2 - Used pm_runtime_resume_and_get() API instead of pm_runtime_get_sync() as suggested by Dan. - Handled the return value in ether_wakeup_host to print error message. When a USB link is idle, the host sends a bus suspend event to the device so that the device can save power. But true power savings during bus suspend can be seen only if we let the USB controller enter low power mode and turn off the clocks. Vendor drivers may have their own runtime power management framework to power up/down the controller. But since vendor drivers' runtime suspend/resume routines depend on the dwc3 child node we would need a framework to trigger dwc3 runtime pm ops whenever a bus suspend is received. If the device wants to exit from bus suspend state it can send a wakeup signal to the host by first bringing out the controller from low power mode. This series implements the needed framework to achieve this functionality when a bus suspend interupt is received. The assumption here is that the dwc3 hibernation feature is not enabled and the platform is responsible in detecting the resume events to bring the controller out of suspend. On Qualcomm platforms the bus resume is handled through Phy and informed to software through wakeup capable phy interrupts. usb2 PHY is configured to detect the Resume K event and sends an interrupt when this event is detected. This would trigger the runtime resume of the glue driver which would intrinsically wakeup the dwc3 child. In case of usb3 PHY, it is configured to detect the LFPS wake signal during bus resume and the corresponding interrupt triggers the runtime resume of the glue driver. The series is organized in below fashion: Patch 1: This includes the modification needed from function drivers to let UDC enter low power mode with u_ether as an example. Patch 2: New dt property to allow dwc3 runtime suspedn during bus suspend scenario. Patch 3: This has the modification needed in the UDC driver to trigger runtime suspend whene a bus suspend interrupt is received. Since this is a platform dependent change it is made applicable through a dt property. This also handles resume and remote wakeup modifications from power management perspective. Elson Roy Serrao (3): usb: function: u_ether: Handle rx requests during suspend/resume dt-bindings: usb: snps,dwc3: Add allow-rtsusp-on-u3 property usb: dwc3: Modify runtime pm ops to handle bus suspend .../devicetree/bindings/usb/snps,dwc3.yaml | 5 ++ drivers/usb/dwc3/core.c | 26 ++++++++-- drivers/usb/dwc3/core.h | 3 ++ drivers/usb/dwc3/gadget.c | 40 +++++++++++++--- drivers/usb/gadget/function/u_ether.c | 47 +++++++++++++++---- 5 files changed, 102 insertions(+), 19 deletions(-) -- 2.17.1
