linux-kernel - Re: [PATCH v2 1/4] dt-bindings: bluetooth: add 'qcom,product-variant'

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Message-ID: <CAA8EJpqAOD_+SLG2LbiodWOs28_rquvMefmSH5CY1yB_rkiZPg@mail.gmail.com>
Date: Thu, 21 Nov 2024 06:38:33 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Cheng Jiang <quic_chejiang@...cinc.com>
Cc: Marcel Holtmann <marcel@...tmann.org>, Luiz Augusto von Dentz <luiz.dentz@...il.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>, 
	Balakrishna Godavarthi <quic_bgodavar@...cinc.com>, Rocky Liao <quic_rjliao@...cinc.com>, 
	quic_zijuhu@...cinc.com, linux-bluetooth@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, quic_mohamull@...cinc.com
Subject: Re: [PATCH v2 1/4] dt-bindings: bluetooth: add 'qcom,product-variant'

On Thu, 21 Nov 2024 at 06:02, Cheng Jiang <quic_chejiang@...cinc.com> wrote:
>
> Hi Dmitry,
>
> On 11/20/2024 6:43 PM, Dmitry Baryshkov wrote:
> > On Wed, Nov 20, 2024 at 05:54:25PM +0800, Cheng Jiang wrote:
> >> Several Qualcomm projects will use the same Bluetooth chip, each
> >> focusing on different features. For instance, consumer projects
> >> prioritize the A2DP SRC feature, while IoT projects focus on the A2DP
> >> SINK feature, which may have more optimizations for coexistence when
> >> acting as a SINK. Due to the patch size, it is not feasible to include
> >> all features in a single firmware.
> >>
> >> Therefore, the 'product-variant' devicetree property is used to provide
> >> product information for the Bluetooth driver to load the appropriate
> >> firmware.
> >>
> >> If this property is not defined, the default firmware will be loaded,
> >> ensuring there are no backward compatibility issues with older
> >> devicetrees.
> >>
> >> The product-variant defines like this:
> >>   0 - 15 (16 bits) are product line specific definitions
> >>   16 - 23 (8 bits) are for the product line.
> >>   24 - 31 (8 bits) are reserved for future use, 0 currently
> >
> > Please use text strings instead of encoding this information into random
> > integers and then using just 3 bits out of 32.
> Ack. Originally intended to make it more flexible for future use. It can be
> text strings for current requirement.

No, fixed-format data isn't flexible. Fine-grained properties are.
Please define exactly what is necessary rather than leaving empty
holes "for future expansion".=

> >
> >>
> >> |---------------------------------------------------------------------|
> >> |                       32 Bits                                       |
> >> |---------------------------------------------------------------------|
> >> |  31 - 24 (bits)   |    23 - 16 (bits)   | 15 - 0 (16 bits)          |
> >> |---------------------------------------------------------------------|
> >> |   Reserved        |    0: default       | 0: default                |
> >> |                   |    1: CE            |                           |
> >> |                   |    2: IoT           |                           |
> >> |                   |    3: Auto          |                           |
> >> |                   |    4: Reserved      |                           |
> >> |---------------------------------------------------------------------|
> >>
> >> Signed-off-by: Cheng Jiang <quic_chejiang@...cinc.com>
> >> ---
> >>  .../bindings/net/bluetooth/qualcomm-bluetooth.yaml          | 6 ++++++
> >>  1 file changed, 6 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml b/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
> >> index 7bb68311c609..9019fe7bcdc6 100644
> >> --- a/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
> >> +++ b/Documentation/devicetree/bindings/net/bluetooth/qualcomm-bluetooth.yaml
> >> @@ -110,6 +110,12 @@ properties:
> >>      description:
> >>        boot firmware is incorrectly passing the address in big-endian order
> >>
> >> +  qcom,product-variant:
> >> +    $ref: /schemas/types.yaml#/definitions/uint32
> >> +    description:
> >> +      specify the product information for driver to load the appropriate firmware
> >
> > DT describes hardware. Is this a hardware property?
>
> It has been added to identify the firmware image for the platform. The driver
> parses it, and then the rampatch is selected from a specify directory. Currently,
> there is a 'firmware-name' parameter, but it is only used to specify the NVM
> (config) file. We also need to specify the rampatch (TLV file).
>
>
> Can we re-use the "firmware-name"? add two segments like the following?
> firmware-name = "rampatch_xx.tlv",  "nvm_xx.bin";

I think this is the better solution

>
> Or add a new property to specify the rampatch file?
> rampatch-name = "rampatch_xx.tlv";
>
> >
> >> +
> >> +
> >>  required:
> >>    - compatible
> >>
> >> --
> >> 2.25.1
> >>
> >
>


-- 
With best wishes
Dmitry