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.

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 .../devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml b/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
index eba2f3026ab0..fdaea08e7442 100644
--- a/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
+++ b/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
@@ -94,6 +94,10 @@ properties:
 
   local-bd-address: true
 
+  qcom,local-bd-address-broken:
+    type: boolean
+    description:
+      boot firmware is incorrectly passing the address in big-endian order
 
 required:
   - compatible
-- 
2.43.2

On Wed, 20 Mar 2024 08:55:51 +0100, Johan Hovold 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.
> 
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> ---
>  .../devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml | 4 ++++
>  1 file changed, 4 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>