[PATCH 1/3] arm64: dts: rockchip: Enable USB 2.0 host1 on Radxa ROCK 3B

[Alexey Charkov]

On Fri, Sep 25, 2026 at 5:56 PM Adam Wermuth <adam at wermuth.pl> wrote:
>
> Hi,
>
> On Thu, 25 Sep 2026 3:26 PM, Sebastian Reichel wrote:
> > Why would this be better suited as an Overlay? Nothing describes the
> > specific card plugged in as it is auto-discovered via USB. The
> > overlays are mostly required for things that cannot easily be
> > auto-detected. FWIW we don't have M.2 Key M as a DT overlay either.
>
> The overlay was Jonas' suggestion, so I'll let him explain his
> reasoning. My own understanding was that it would avoid powering the
> slot (always-on supply plus RESET#/W_DISABLE1# hogs) on boards where
> nothing is plugged in.
>
> That said, I agree that the module itself is auto-discovered via USB,
> and the Key M slot on this board is described in the base DT as well,
> so I'm fine with keeping the B-key slot there, as in v1.
>
> > Something to consider is, that for Key E and Key M there is a proper
> > DT binding now: Documentation/devicetree/bindings/connector/pcie-m2-*.yaml
> >
> > We probably want the same for Key B.
>
> Thanks for the pointer. As far as I can see, a Key B binding would
> also need driver support to handle the supply, RESET# and W_DISABLE1#,
> so it is a larger piece of work. Would it be acceptable to describe
> the slot in the base DT for now and move to a connector binding once
> one exists for Key B?

Key B binding would be somewhat more involved than key E or key M. The
spec defines 16 distinct interface mux configurations selected by the
four CONFIG_X pins, which neither key M nor key E have (PCIe vs. SATA,
USB3 vs. SSIC, different audio configs, different I2C configs, etc.).
So it's a bit more than the supply, RESET# and W_DISABLE1#.

See for example [1] where just the PCIe vs. SATA selection is defined.
A proper binding will be needed sooner or later, though.

[1] https://github.com/flipperdevices/u-boot/blob/rk3576/board/flipper/flipper-one/flipper-one-rk3576.c#L41-L172

Best regards,
Alexey