Re: [PATCH v3 1/5] dt-bindings: bluetooth: add 'qcom,local-bd-address-broken'

[Doug Anderson]

Hi,

On Tue, Mar 19, 2024 at 8:29 AM Johan Hovold <johan+linaro@xxxxxxxxxx> wrote:
>
> Several Qualcomm Bluetooth controllers lack persistent storage for the
> device address and instead one can be provided by the boot firmware
> using the 'local-bd-address' devicetree property.
>
> The Bluetooth bindings clearly states that the address should be
> specified in little-endian order, but due to a long-standing bug in the
> Qualcomm driver which reversed the address some boot firmware has been
> providing the address in big-endian order instead.
>
> The only device out there that should be affected by this is the WCN3991
> used in some Chromebooks.
>
> Add a 'qcom,local-bd-address-broken' property which can be set on these
> platforms to indicate that the boot firmware is using the wrong byte
> order.
>
> Note that ChromeOS always updates the kernel and devicetree in lockstep
> so that there is no need to handle backwards compatibility with older
> devicetrees.
>
> Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
> ---
>  .../devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml  | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml b/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
> index eba2f3026ab0..e099ef83e7b1 100644
> --- a/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
> +++ b/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
> @@ -94,6 +94,9 @@ properties:
>
>    local-bd-address: true
>
> +  qcom,local-bd-address-broken: true
> +    description: >
> +      boot firmware is incorrectly passing the address in big-endian order

Personally, I feel like "qcom,local-bd-address-backwards" or
"qcom,local-bd-address-swapped" would be more documenting but I don't
feel super strongly about it. I guess "broken" makes it more obvious
that this is not just a normal variant that someone should use. If DT
binding folks are happy, I'm happy enough with this solution.

Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>