> Hi Krzysztof,
>
> Thank you for reviewing the patch.
>
> >
> > On 16/06/2025 17:09, Neeraj Sanjay Kale wrote:
> > > Add support for 4000000 as secondary baudrate for downloading FW
> > > chunks and after HCI initialization is done at fw-init-baudrate.
> > >
> > > Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@xxxxxxx>
> > > ---
> > > .../bindings/net/bluetooth/nxp,88w8987-bt.yaml | 10 ++++++++++
> > > 1 file changed, 10 insertions(+)
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
> bt.yam
> > > l
> > > b/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
> bt.yam
> > > l index 3ab60c70286f..f1c7f900001c 100644
> > > ---
> > > a/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
> bt.yam
> > > l
> > > +++ b/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
> bt
> > > +++ .y
> > > +++ aml
> > > @@ -34,6 +34,16 @@ properties:
> > > This property depends on the module vendor's
> > > configuration.
> > >
> > > + secondary-baudrate:
> > > + $ref: /schemas/types.yaml#/definitions/uint32
> >
> > baudrate is in some value, so use unit suffix from property-units and
> > drop the ref.
> In property-units.yaml, I can see "-bps" with ref type uint32.
> I will change this property to "secondary-baudrate-bps" and drop ref in v2
> patch.
>
> >
> > And then you will see that it could be actually an array, so why not
> > using existing properties? Otherwise you will add soon "tertiary" etc?
> > This does not scale.
> >
>
> There won't be a tertiary baudrate as far as I know.
> Also, if we remove the existing fw-init-baudrate property to combine fw-init-
> baudrate and secondary baudrate in an array, it would cause backward
> compatibility issues for existing customers.
>
> Let me explain the objective here.
> The NXP BT chip will power-on and bootloader will always configure it at
> 115200 baudrate, even for the planned future chipsets.
> The driver will read chip signature and flags to select the chip specific FW file
> and set the chip baudrate to a higher/secondary baudrate for the actual FW
> download.
>
> Once FW download is complete, FW will initialize and based on module
> vendor's OTP setting set the chip's UART baudrate to "fw-init-baudrate".
> HCI initialization will happen at this fw-init-baudrate, and post-init, driver will
> set chip baudrate to higher/secondary baudrate for normal operation.
>
> Currently, this higher/secondary baudrate is hardcoded to 3000000 in driver.
> But if BT chip and host processor are close-by, or mounted on the same PCB,
> UART communication at 4000000 is possible.
>
> This can be achieved by adding the new device tree property "secondary-
> baudrate-bps = <4000000>".
>
> Connections with FRC cables or fly-wires show command timeout errors at
> 4000000 baudrate.
> Hence, we keep default secondary baudrate as 3000000.
>
> Please let me know, based on above explanation if we should change the
> baudrate parameter to array in DT and Driver.
>
Can the existing "max-speed" property be used in this context as an enum?
max-speed: true
enum:
- 3000000
- 4000000
Thanks,
Neeraj
