Hi,
Removing mugunthanvnm@ti.com, who is no longer working for TI.
On Wednesday 06 September 2017 02:02 AM, Maxime Ripard wrote:
Hi,
I've been working with USB-Ethernet gadget for quite some time on the Allwinner SoCs, especially because most Allwinner boards lack an ethernet controller.
The thing is, it wasn't really upstreamable all this time since we've had also some boards that had a controller with DM_ETH. And usb_ether didn't have DM_ETH support until recently.
So I gave it a shot, and encountered a few weird things that prevented it from working (and still do):
I converted our musb glue to support the DM even in the peripheral mode. Here is the code: http://code.bulix.org/m846ni-194479
It almost works, except that usb_scan_bus in usb-uclass.c for some reason unknown to me tries to scan the peripheral device, and fails. Skipping that scan makes fastboot works, so I guess the peripheral is working. Is there any particular reason that the DM_USB code tries to scan even peripheral devices ?
I can't manage to get usb_ether to probe after that, using the DM. It seems that we need to call usb_ether_init, and that it looks for UCLASS_USB_DEV_GENERIC devices and binds the usb_ether gadget to it.
However, every board or arch hooks I tried seems to be much earlier than the USB controller, leading to the binding failing since we don't have a controller to bind to yet.
am33xx probes MISC devices in arch_misc_init() (arch/arm/mach-omap2/am33xx/board.c)
Adding that code right after the USB controller initialisation in the musb probe solves that issue, but for some other reason, it looks for a device of the USB_DEV_GENERIC uclass, while the uclass for the USB controllers seems to be USB. Actually, I don't seem to find any user of the USB_DEV_GENERIC uclass but the usb_ether driver, so I'm not really sure how it's supposed to work either...
Sorry, DM based eth gadget support is still missing for am33xx. This patch in particular was asked to be reworked: https://patchwork.ozlabs.org/patch/696033/
Is there some user of this in U-Boot right now? the only call there is to usb_ether_init seems to be for the am33xx SoCs, whose usb glue don't register a peripheral controller (yet), so I don't really know how that can work either.
Last time I tried to upstream dwc3 usb ethernet gaget and rndis boot support, Lukasz Majewski had ideas to move towards adding DM infrastructure for USB gadget: https://patchwork.ozlabs.org/patch/775110/