On Mon, Dec 09, 2024 at 02:32:37PM +0200, Roger Quadros wrote: Hello Roger,
> On 06/12/2024 12:07, Siddharth Vadapalli wrote: [...] > > Looking at the list of compatibles in dwc3-generic.c and focusing on the > > compatible "ti,keystone-dwc3", I see that this compatible is present in: > > dts/upstream/src/arm/ti/keystone/keystone.dtsi > > among other keystone device-tree files. The hierarchy of the nodes and > > compatibles for the USB Subsystem and the USB Controller in Keystone is > > similar to that of AM62*. The difference however is the following: > > A) For non AM62* devices: > > note there are 2 cases here: > > A1) that enable CONFIG_USB_DWC3_GENERIC > > > USB Subsystem [Wrapper] driver is dwc3-generic.c > Yes. > > > USB Controller [DWC3] driver is xhci-dwc3.c > > No. > > Note that none of the platforms that enable CONFIG_USB_DWC3_GENERIC > enable CONFIG_USB_XHCI_DWC3. They should not because dwc3-generic.c > takes care of registering the XHCI driver via xhci_register/deregister() Thank you for pointing this out. > > A2) that don't enable CONFIG_USB_DWC3_GENERIC > > These are usually only interested in host mode, they enable > CONFIG_USB_XHCI_DWC3 and may also enable CONFIG_USB_XHCI_DWC3_OF_SIMPLE > > So USB Wrapper/glue driver is DWC3_OF_SIMPLE > USB driver is xhci-dwc3.c > > Some platforms have their own glue > CONFIG_USB_XHCI_STI dwc3-sti-glue.c > CONFIG_USB_XHCI_OCTEON dwc3-octeon-glue.c > > > B) For AM62* devices: > > USB Subsystem [Wrapper] driver is dwc3-am62.c > > which exposes its own ".glue_configure" callback similar to what > > is done in dwc3-generic.c for other devices. > > The Subsystem driver is still dwc3-generic.c. Glue driver is dwc3-am62.c > > > USB Controller [DWC3] driver is xhci-dwc3.c > > No. > We don't require CONFIG_USB_XHCI_DWC3 as XHCI registration is done > by dwc3-generic. USB Host driver is USB_XHCI_HCD. Ok. > > > So maybe non AM62* devices have: > > dwc3-generic.c for Subsystem + xhci-dwc3.c for USB Controller > > while AM62* devices have: > > dwc3-am62.c for Subsystem + dwc3-generic.c (neither Subsystem > > nor Controller?) + xhci-dwc3.c for USB Controller > > We could probably end up with the two driver situation similar to non > > AM62* devices if we update dwc3-generic.c to handle the configuration > > performed by dwc3-am62.c. But that still means we have two drivers: > > dwc3-generic.c and xhci-dwc3.c > > Maybe viewing the output of "dm tree" on a non AM62* device with both > > CONFIG_USB_XHCI_DWC3 and CONFIG_USB_DWC3_GENERIC enabled will let us > > know whether that is a valid configuration or not. > > Enabling both is an invalid configuration and no config does it. AM62 was > doing it wrong and so we fix it with this patch. Understood. Thank you for explaining. I agree that the fix in this patch is correct and your earlier suggestion of Kconfig guards: "Maybe we still need some Kconfig guards that prevent both CONFIG_USB_XHCI_DWC3 and USB_DWC3_GENERIC to be set together as 2 drivers will claim the controller if dr_mode is USB_DR_MODE_OTG or USB_DR_MODE_HOST." could be implemented in a follow up patch. Regards, Siddharth.
