Message-ID: <63d40318.050a0220.b303.8deb@mx.google.com>
Date:   Fri, 27 Jan 2023 11:00:06 -0600
From:   Chris Morgan <macroalpha82@gmail.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc:     linux-bluetooth@vger.kernel.org, devicetree@vger.kernel.org,
        alistair@alistair23.me, anarsoul@gmail.com,
        krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org,
        marcel@holtmann.org, johan.hedberg@gmail.com, luiz.dentz@gmail.com,
        max.chou@realtek.com, hildawu@realtek.com,
        Chris Morgan <macromorgan@hotmail.com>
Subject: Re: [PATCH RFC 1/2] dt-bindings: net: realtek-bluetooth: Add
 RTL8821CS
References: <20230126165529.1452252-1-macroalpha82@gmail.com>
 <20230126165529.1452252-2-macroalpha82@gmail.com>
 <02bddab6-4c63-bb39-9a11-8dab81322c28@linaro.org>
 <63d3fff7.050a0220.db92.7af4@mx.google.com>
 <ed5fec12-1c86-d235-718f-f812e7461d94@linaro.org>
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On Fri, Jan 27, 2023 at 05:53:49PM +0100, Krzysztof Kozlowski wrote:
> On 27/01/2023 17:46, Chris Morgan wrote:
> > On Fri, Jan 27, 2023 at 11:24:03AM +0100, Krzysztof Kozlowski wrote:
> >> On 26/01/2023 17:55, Chris Morgan wrote:
> >>> From: Chris Morgan <macromorgan@hotmail.com>
> >>>
> >>> Add compatible string for RTL8821CS for existing Realtek Bluetooth
> >>> driver.
> >>>
> >>> Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
> >>> ---
> >>>  Documentation/devicetree/bindings/net/realtek-bluetooth.yaml | 1 +
> >>>  1 file changed, 1 insertion(+)
> >>>
> >>
> >> Based on your driver it is compatible with rtl8822cs, so you can
> >> indicate it in the binding and use just one of_device_id entry.
> > 
> > It's very similar, and uses some of the same constants, but has a
> > different firmware. I assumed the firmware difference is enough to
> > require it to be differentiated, but I wasn't sure. You are saying
> > it does not? I just want to be clear.
> 
> If by "differentiated" you mean "incompatible", then depends:
> 1. You have firmware-name property to indicate the firmware to load and
> then you can use one compatible to bind and just load different firmware,
> 2. If device variant is autodectable, it's compatible.
> 
> realtek,rtl8723ds-bt also was added to the driver uselessly...

Gotcha.

They are incompatible, but the driver should be able to autodetect each
device as best I can tell. In fact all of the devices listed in the
bindings should be autodetectable by the driver (again, as best I can
tell). Honestly though that's assuming I'm using the correct firmware,
which is why I have this tagged as an RFC. I'm really hoping to get
Realtek's attention for them to chime in to confirm I'm using the
most recent firmware and under what license/terms the firmware can
be redistributed so that the firmware may be added to linux-firmware.

Assuming everything is good though, I can resubmit V2 and instead of
adding a new compatible just noting that the 8822CS and 8821CS use
the same bindings.

Thank you.

> 
> Best regards,
> Krzysztof
>