Message-ID: <8cf45912-1fda-dd3e-4051-fa4930f8860d@linaro.org>
Date:   Fri, 27 Jan 2023 18:02:06 +0100
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Subject: Re: [PATCH RFC 1/2] dt-bindings: net: realtek-bluetooth: Add
 RTL8821CS
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To:     Chris Morgan <macroalpha82@gmail.com>
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>
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>
 <63d40318.050a0220.b303.8deb@mx.google.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <63d40318.050a0220.b303.8deb@mx.google.com>
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Precedence: bulk

On 27/01/2023 18:00, Chris Morgan wrote:
> 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.

They cannot use the same bindings. You always need specific compatible
and this was not discussed here. What's discussed is to drop the driver
change in of_device_id.

Best regards,
Krzysztof