On Mon, 18 Mar 2024 at 15:17, Johan Hovold <[email protected]> wrote:
>
> On Mon, Mar 18, 2024 at 03:00:40PM +0200, Dmitry Baryshkov wrote:
> > On Mon, 18 Mar 2024 at 13:09, Johan Hovold <[email protected]> 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 says 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 bootloaders have 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. To maintain backwards compatibility, mark the
> > > current compatible string as deprecated and add a new
> > > 'qcom,wcn3991-bt-bdaddr-le' for firmware which conforms with the
> > > binding.
>
> > This compatible doesn't describe new hardware kind. As such, I think,
> > the better way would be to continue using qcom,wcn3991-bt compatible
> > string + add some kind of qcom,bt-addr-le property.
>
> No, you can't handle backwards compatibility by *adding* a property.
>
> I wanted to avoid doing this, but if we have to support Google's broken
> boot firmware for these devices, then this is how it needs to be done.
One hardware compat string per hardware type.
--
With best wishes
Dmitry
On Mon, Mar 18, 2024 at 04:17:24PM +0200, Dmitry Baryshkov wrote:
> On Mon, 18 Mar 2024 at 15:17, Johan Hovold <[email protected]> wrote:
> > On Mon, Mar 18, 2024 at 03:00:40PM +0200, Dmitry Baryshkov wrote:
> > > On Mon, 18 Mar 2024 at 13:09, Johan Hovold <[email protected]> wrote:
> > > > The only device out there that should be affected by this is the WCN3991
> > > > used in some Chromebooks. To maintain backwards compatibility, mark the
> > > > current compatible string as deprecated and add a new
> > > > 'qcom,wcn3991-bt-bdaddr-le' for firmware which conforms with the
> > > > binding.
> >
> > > This compatible doesn't describe new hardware kind. As such, I think,
> > > the better way would be to continue using qcom,wcn3991-bt compatible
> > > string + add some kind of qcom,bt-addr-le property.
> >
> > No, you can't handle backwards compatibility by *adding* a property.
> >
> > I wanted to avoid doing this, but if we have to support Google's broken
> > boot firmware for these devices, then this is how it needs to be done.
>
> One hardware compat string per hardware type.
Again, no. Not when there is an incompatible change in the binding. Then
we add a new compatible string and deprecate the old binding.
Johan