On 9/15/26 9:57 AM, Stefan Eichenberger wrote:
On Mon, Sep 14, 2026 at 09:31:25PM +0200, Marek Vasut wrote:
On 9/14/26 9:42 AM, Stefan Eichenberger wrote:
From: Stefan Eichenberger <[email protected]>
The i.MX95 SoC has two USB controllers, a DWC3 controller and a ChipIdea
controller. However, U-Boot might select a controller that is marked as
host only in the device tree when attempting to set up a USB gadget,
leading to failures in gadget mode.
Iterate over usb devices and skipping any that are marked host-only when
selecting the controller for gadget mode. This ensures that a controller
that is marked as device or otg is used for USB gadget functionality.
Verified on Verdin iMX95 hardware: "ums 0 mmc 0" now correctly flips
the ChipIdea OTG controller into device mode and enumerates on the
host PC.
What was the previous incorrect behavior ?
When I did a ums 0 mmc 0, the host only DWC3 controller was selected. It
is not host only by itself, but it is marked as host only for our board
in the device tree.
Does your board DT have /aliases { usb0 = &... } entry pointing to the
chipidea controller already ? The controller indexing should match the
aliases ordering.
Yes we use aliases. Interstingly the dwc3 controller is usb1 and the
chipidea controller is usb0.
aliases {
...
usb0 = &usb2;
usb1 = &usb3;
...
};
&usb2 {
dr_mode = "otg";
...
};
&usb3 {
...
&usb3_dwc3 {
dr_mode = "host";
};
...
};
So it seems this ordering is not respected when selecting the controller
for gadget mode. I have to test that again. However, I still think host
only devices should never be selected for gadget mode which is what this
patch tries to address. Or should e.g. ums 1 mmc 0 just fail for host
only controllers?
Yes
In this scenario I assume the ordering is correct so
ums 1 would select the dwc3 host only controller.
The ordering should respect the aliases enumeration, so ums 0 ... is CI
HDRC and ums 1 is DWC3 . Can you check the U-Boot control DT /aliases
node to be sure the ordering there is as expected ?
=> fdt addr $fdtcontroladdr
=> fdt print /aliases
