Hi Vignesh,
Hi Sherry,
[...]
AFAIK, U-Boot does not support runtime switching of USB port to host from device and vice versa. This is the case for existing driver like
DWC3/MUSB etc.
Ideally we would need a role switch driver that unbinds and rebinds host vs device driver as when required based on U-Boot cmd or via an API (if required to be done during SPL stage etc).
I wonder if we can add two subnodes under the wrapper node as below,
one bind to usb gadget driver and another bind to usb host driver.
So if we want to use usb device, just call the gadget driver, and if want to
use usb host, just call the host driver. The driver will probe correspond node.
I'm not sure if it is feasible, what do you think about it?
usbss0: cdns_usb@4104000 { compatible = "ti,j721e-usb"; [....] usb0: usb@6010000 { /* xhci reg address*/ compatible = "cdns,usb3-1.0.1";dr_mode = "host"; [....] } usb1: usb@6020000 { /* dev reg address*/ compatible = "cdns,usb3-1.0.1"; dr_mode = "peripheral"; [....] } }
But this is not how DT would look in kernel. There will be single DT node representing both Host and Device node. DT repesentation should not be changed based on OS/bootloader, its HW description and must remain same. Unbinding host/gadget driver and rebinding with a different role should not be hard as the U-Boot core infrastructure exists.
Moreover if xhci reg and dev reg are separated into different nodes dont we still need access to OTG register block to switch b/w host and device mode?
I think we may not need to access OTG register if we add two subnodes for gadget and host.
But I see a for loop in dwc3_glue_bind() as follows, if there only one single node representing both Host and Device node under usb wrapper node, why we need this for loop?
212 for (node = fdt_first_subnode(fdt, dev_of_offset(parent)); node > 0; 213 node = fdt_next_subnode(fdt, node)) {
Best regards Sherry sun
Regards Vignesh
Best regards Sherry sun
Regards Vignesh
Best regards Sherry sun
JJ
> Then when binding the wrapper node, it will hard-coded the two
subnodes
> to different driver(gadge/host driver) according to the dr_mode > property
in
> nodes. > Do you think I understand it right?
Best regards Sherry sun
> Best regards > Sherry sun > >> JJ >> >> >> >>>>>>>> + { } >>>>>>>> +}; > _______________________________________________ > U-Boot mailing list > U-Boot@lists.denx.de > https://l >
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-- Regards Vignesh