On 12/01/2024 13:06, Sjoerd Simons wrote:
On Fri, 2024-01-12 at 12:39 +0200, Roger Quadros wrote:
On 12/01/2024 10:52, Sjoerd Simons wrote:
When dr_mode is "otg" the dwc3 is initially configured in _OTG mode; However in this mode the gadget functionality doesn't work without further configuration. To resolve that on gadget start switch to _DEVICE mode globally and go back to _OTG on stop again.
For this the dwc3_set_mode is renamed to dwc3_core_set_mode to avoid a conflict with the same function exposed by xhci-dwc3
Aren't they both doing the same thing? I'd rather define them at one place i.e. dwc3/core.c.
They twiddle the same registers afaict indeed; but the way to get there is rather different. So having just one for both really needs a bigger amount of rework.
The driver model design for dwc3 looks really broken in u-boot.
"snps,dwc3" is claimed by xhci-dwc3.c instead of being claimed by dwc3/core.c. This is probably because at the time USB host was the more needed use case at u-boot.
Ideally dwc3/core.c should claim "snps,dwc3" device and instantiate the respective Host/Device/OTG device based on the provided otg mode.
For Host/Device mode it is straight forwa dwc3/core.c does dwc3_set_mode() depending on the mode and: for host mode -> register xhci-usb driver. for device mode -> register UDC device driver.
For dual-role mode, the solution is not very clear as I don't think there is a role switch framework present
To begin with, we could probably restrict it to just device mode as most platforms were forcing it to device mode in any case as they usually have a 2nd USB port that is host only.
Right we don't have role switching; And if we had we'd have to add support of the Type-C controller on the SK boards which determines the roles for this.
This one more minimal patch was modelled after the discussion last year around otg mode[0]. And similar to how the cdns3 driver handles it. Essentially letting host/gadget mode be determined by the usage rather then the cables plugged, which is not pretty but works.
While I agree with you this could all be a lot nicer of u-boot did "proper" OTG/role-switching; I unfortunately don't have the bandwidth to introduce all of that and it seems a shame to block DFU support on it. For reference my previous series just set the peripheral role in the dts which reflects your suggestion of forcing device mode. I'd be wary to do so in the driver because i would hope the OTG handling in dwc3 is there for a reason :)
0: https://lists.denx.de/pipermail/u-boot/2023-August/527709.html
In your current series, how does it work? What happens if user starts both host and device controllers?
e.g.
usb start dfu 0