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Message-ID: <a4324473-e0c6-4d53-8de0-03b69480e40b@linaro.org>
Date: Tue, 30 Jan 2024 08:37:15 +0100
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Subject: Re: [PATCH v2 1/2] dt-bindings: net: bluetooth: Add MediaTek MT7921S
 SDIO Bluetooth
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To: Chen-Yu Tsai <wenst@chromium.org>
Cc: Marcel Holtmann <marcel@holtmann.org>,
 Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
 Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Matthias Brugger
 <matthias.bgg@gmail.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>,
 Sean Wang <sean.wang@mediatek.com>, linux-bluetooth@vger.kernel.org,
 netdev@vger.kernel.org, linux-mediatek@lists.infradead.org,
 devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 linux-kernel@vger.kernel.org
References: <20240126063500.2684087-1-wenst@chromium.org>
 <20240126063500.2684087-2-wenst@chromium.org>
 <74b9f249-fcb4-4338-bf7b-8477de6c935c@linaro.org>
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From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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On 30/01/2024 04:32, Chen-Yu Tsai wrote:
> On Mon, Jan 29, 2024 at 3:34 PM Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>>
>> On 29/01/2024 04:38, Chen-Yu Tsai wrote:
>>
>>>>> +allOf:
>>>>> +  - $ref: bluetooth-controller.yaml#
>>>>> +
>>>>> +properties:
>>>>> +  compatible:
>>>>> +    enum:
>>>>> +      - mediatek,mt7921s-bluetooth
>>>>
>>>> Can it be also WiFi on separate bus? How many device nodes do you need
>>>> for this device?
>>>
>>> For the "S" variant, WiFi is also on SDIO. For the other two variants,
>>> "U" and "E", WiFi goes over USB and PCIe respectively. On both those
>>> variants, Bluetooth can either go over USB or UART. That is what I
>>> gathered from the pinouts. There are a dozen GPIO pins which don't
>>> have detailed descriptions though. If you want a comprehensive
>>> binding of the whole chip and all its variants, I suggest we ask
>>> MediaTek to provide it instead. My goal with the binding is to document
>>> existing usage and allow me to upstream new device trees.
>>>
>>> For now we only need the Bluetooth node. The WiFi part is perfectly
>>> detectable, and the driver doesn't seem to need the WiFi reset pin.
>>> The Bluetooth driver only uses its reset pin to reset a hung controller.
>>
>> Then suffix "bluetooth" seems redundant.
> 
> I think keeping the suffix makes more sense though. The chip is a two
> function piece, and this only targets one of the functions. Also, the

That's why I asked and you said there is only one interface: SDIO.

> compatible string is already used in an existing driver [1] and
> soon-to-be in-tree device tree [2].

That's not the way to upstream compatible. You cannot send it bypassing
bindings and review and later claim that's an ABI.


Best regards,
Krzysztof