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

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Message-ID: <CAA8EJpqpzwGL38F_MYUJVuAT8q96QZO7CSh00ZpNBU5cGWUqqA@mail.gmail.com>
Date: Sat, 30 Nov 2024 10:24:26 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: "Cheng Jiang (IOE)" <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 Sat, 30 Nov 2024 at 05:48, Cheng Jiang (IOE)
<quic_chejiang@...cinc.com> wrote:
>
> Hi Dmitry,
>
> On 11/21/2024 12:38 PM, Dmitry Baryshkov wrote:
> > 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
> >
> How about the following logic for handling 'firmware-name' property:
> 1. If there is only one string in firmware-name, it must be the NVM file, which is used
>    for backward compatibility.
>
> 2. If there are two strings in firmware-name, the first string is for the rampatch, and
>    the second string is for the NVM.

I'd say, other way around: the first one is always NVM, the second one
is rampatch and it is optional.

>
> 3. Due to variations in RF performance of chips from different foundries, different NVM
>    configurations are used based on the board ID. If the second string ends with boardid,
>    the NVM file will be selected according to the board ID.

Is there a reason why you can not use the exact firmware name? The
firmware name is a part of the board DT file. I assume you know the
board ID that has been used for the board.

>
>
> Here are two examples:
>
>  firmware-name = "qca/QCA6698/hpbtfw21.tlv",  "qca/QCA6698/hpnv21.bin";
> In this configuration, the driver will use the two files directly.
>
>
>  firmware-name = "qca/QCA6698/hpbtfw21.tlv",  "qca/QCA6698/hpnv21.boardid";
> In this configuration, the driver will replace boardid with the actual board information.
> If the board id is 0x0206, the nvm file name will be qca/QCA6698/hpnv21.b0206
>
> >>
> >> Or add a new property to specify the rampatch file?
> >> rampatch-name = "rampatch_xx.tlv";
> >>
> >>>
> >>>> +
> >>>> +
> >>>>  required:
> >>>>    - compatible
> >>>>
> >>>> --
> >>>> 2.25.1
> >>>>
> >>>
> >>
> >
> >
>

--
With best wishes
Dmitry