Re: [PATCH v2 1/6] dt-bindings: bluetooth: qca: add QCC2072

[Krzysztof Kozlowski <krzk@kernel.org>]

On 07/08/2026 11:57, Dmitry Baryshkov wrote:
> On Sat, Aug 01, 2026 at 05:49:53PM +0200, Krzysztof Kozlowski wrote:
>> On 01/08/2026 17:31, Rahul Samana wrote:
>>>
>>>
>>> On 01-08-2026 20:18, Krzysztof Kozlowski wrote:
>>>> On 31/07/2026 17:51, Rahul Samana wrote:
>>>>>
>>>>>
>>>>> On 31-07-2026 20:34, Krzysztof Kozlowski wrote:
>>>>>> On 31/07/2026 16:45, Rahul Samana wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 31-07-2026 15:16, Krzysztof Kozlowski wrote:
>>>>>>>> On Mon, Jul 27, 2026 at 09:15:01PM +0530, Rahul Samana wrote:
>>>>>>>>> QCC2072 can be used on M.2 E-key cards where the card power resources are
>>>>>>>>> described by the pcie-m2-e-connector node. In that setup, the M.2 power
>>>>>>>>> sequencing provider creates the Bluetooth serdev child after matching the
>>>>>>>>> QCC2072 PCI function.
>>>>>>>>>
>>>>>>>>> Integrated non-M.2 designs need board-specific power resources. Document
>>>>>>>>> only the compatible for now and leave those properties to be added with
>>>>>>>>> matching driver support.
>>>>>>>>>
>>>>>>>>> Document the qcom,qcc2072-bt compatible used for QCC2072 Bluetooth
>>>>>>>>> controllers connected over UART.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Rahul Samana <rahul.samana@oss.qualcomm.com>
>>>>>>>>
>>>>>>>> NAK, exactly same comments as before.
>>>>>>>>
>>>>>>>> Nothing got improved, although what is weird - original SoB is gone, so
>>>>>>>> this is legally dubious work.
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>> Krzysztof
>>>>>>>>
>>>>>>>
>>>>>>> Hi Krzysztof,
>>>>>>>
>>>>>>> Thanks for the review.
>>>>>>>
>>>>>>> For the binding contents, I tried to capture the current scope in the binding
>>>>>>> description itself. This series supports QCC2072 only as an M.2 E-key card,
>>>>>>> where the card power resources are described by the pcie-m2-e-connector node
>>>>>>> and the M.2 pwrseq provider creates the Bluetooth serdev child.
>>>>>>>
>>>>>>> The binding also says:
>>>>>>>
>>>>>>>   Integrated non-M.2 designs require board-specific power resources. Those
>>>>>>>   properties, together with a static devicetree example, should be added when
>>>>>>>   integrated non-M.2 support is added.
>>>>>>
>>>>>> Bindings must be complete and your driver support is irrelevant here.
>>>>>>
>>>>>> If you claim this is a PCI device thus you do not need any resources,
>>>>>> then the binding is not needed either. PCI devices are enumerable. And
>>>>>> to prove it: look at your DTS. Do you see qcom,qcc2072-bt being used? No.
>>>>>>
>>>>>>>
>>>>>>> We do not currently have an integrated non-M.2 QCC2072 design, so I do not
>>>>>>> have board-specific regulator supplies to document for that topology.
>>>>>>>
>>>>>>> Could you please suggest how you would prefer this binding to be handled for
>>>>>>> the current M.2-only use case? 
>>>>>>
>>>>>> Drop the binding, you do not need it.
>>>>>>
>>>>>> Anyway the problem is that more comments were ignored.
>>>>>>
>>>>>
>>>>> Hi Krzysztof,
>>>>>
>>>>> Just to clarify the reason for adding this binding in v2: 
>>>>> v1 did not add a binding because this series only targets the M.2 use case.
>>>>>
>>>>> I added the minimal binding in v2 because checkpatch reported
>>>>> qcom,qcc2072-bt as an undocumented compatible, and I interpreted the request
>>>>> to fix the checkpatch warnings as requiring this compatible to be documented.
>>>>> I also had the earlier feedback in mind, where the indirect
>>>>> qcom,qcc2072-bt compatible was pushed back because it was undocumented:
>>>>>
>>>>> https://lore.kernel.org/all/20260703-eliza_evk-v1-3-7624440bd76d@oss.qualcomm.com/
>>>>>
>>>>> Based on your clarification here, I will drop the binding patch in v3 and
>>>>> keep qcom,qcc2072-bt only as the pwrseq-created child compatible for this
>>>>> M.2 case.
>>>>
>>>> My previous statement is also valid, please read entire threads.
>>>>
>>>> You cannot have undocumented qcom,qcc2072-bt.
>>>>
>>>> I ask you to drop both, because they are not needed. But feel free to
>>>> prove me wrong, see my first paragraph in the previous reply.
>>>>
>>>>
>>> The PCIe M.2 power sequencing driver, pwrseq-pcie-m2.c, uses
>>> pwrseq_m2_pci_ids to translate the enumerated PCI function into the
>>> Bluetooth compatible used for the generated serdev child.
>>>
>>> For example, WCN7850 maps PCI ID 17cb:1107 to qcom,wcn7850-bt, then hci_qca
>>> matches that compatible to select qca_soc_data_wcn7850.
>>>
>>> For QCC2072, pwrseq-pcie-m2.c matches PCI ID 17cb:1112 and creates the
>>> generated Bluetooth serdev child with compatible "qcom,qcc2072-bt". The
>>> hci_qca driver then matches "qcom,qcc2072-bt" and uses qca_soc_data_qcc2072
>>> as the controller-specific data.
>>
>> The purpose of Devicetree is not to describe Linux internal driver
>> matching. Do not use compatibles for that.
> 
> So, if instead of M.2 module the WiFi chip gets soldered to the main
> board, the qcom,qcc2072-bt wll be a legitimate compat string?

Yes, just like the rest of compatibles in the power sequencing driver
(and bindings).

> 
> Also, I understand your concerns about the DT bindings / usage, but
> speaking about the driver ;-)
> The BT is a serial driver attached to a serial bus. There only two
> options to bind a serial driver: OF and ACPI. But maybe we should add
> something like serial_device_id and let serials have internal IDs.
> It sounded strange in the beginning, but now I think it is a correct way
> to go.

Driver get away with that limitation, because we had DTS for the
existing entries. This is the first one without DTS.

Best regards,
Krzysztof