linux-kernel - Re: [PATCH v2 2/2] dt-bindings: net: bluetooth: Add device property nvm-postfix for QCA6174

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Message-ID: <319cbb5f23ed3d9f1ae77c697001378d@codeaurora.org>
Date:   Tue, 09 Apr 2019 18:15:25 +0800
From:   Rocky Liao <rjliao@...eaurora.org>
To:     Marc Gonzalez <marc.w.gonzalez@...e.fr>
Cc:     marcel@...tmann.org, johan.hedberg@...il.com,
        Matthias Kaehlcke <mka@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-bluetooth@...r.kernel.org,
        MSM <linux-arm-msm@...r.kernel.org>, bgodavar@...eaurora.org,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v2 2/2] dt-bindings: net: bluetooth: Add device property
 nvm-postfix for QCA6174

On 2019-04-04 20:32, Marc Gonzalez wrote:
> +robh
> 
> On 04/04/2019 11:08, Rocky Liao wrote:
> 
>> This patchs patch adds an optional device property nvm-postfix to 
>> allow the
>> driver to load customized nvm file based on this property
> 
> While text /before/ is indeed called a "prefix", text /after/ is not a
> "postfix",
> but a "suffix".
> 
> 
>>  Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt | 2 ++
>>  1 file changed, 2 insertions(+)
>> 
>> diff --git 
>> a/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt 
>> b/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt
>> index 824c0e2..70cda4b 100644
>> --- a/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt
>> +++ b/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt
>> @@ -16,6 +16,7 @@ Optional properties for compatible string 
>> qcom,qca6174-bt:
>> 
>>   - enable-gpios: gpio specifier used to enable chip
>>   - clocks: clock provided to the controller (SUSCLK_32KHZ)
>> + - nvm-postfix: nvm file postfix to load customized nvm file
> 
> The device tree is supposed to describe hardware.
> 
> The name of which file to load can hardly be considered part of the HW.
> 
> Possible solutions:
> 1) derive the file name from the compatible string
> 2) pass the name as a module parameter
> 3) something else
> 
> 
>> @@ -39,6 +40,7 @@ serial@...0000 {
>> 
>>  		enable-gpios = <&pm8994_gpios 19 GPIO_ACTIVE_HIGH>;
>>  		clocks = <&divclk4>;
>> +		nvm-postfix = "i2s";
>>  	};
>>  };
> 
> If one provides the entire suffix, including the underscore, then you 
> can
> simplify the code:
> 
> 	snprintf(config.fwname, sizeof(config.fwname), "qca/nvm_%08x%s.bin",
> soc_ver, suffix ? suffix : "");
> 
> Regards
.
Hi Marc,

The major purpose for that property is about the BT audio bus type, can 
it be considered as part of the HW? If yes maybe we can use a property 
name "audio-bus" to reflect that.

If not then I will adopt the solution 1 to add a new compatible string 
"{ .compatible = "qcom,qca6174-bt-i2s" }" and load specific nvm for this 
compatible string, please feel free to let me know if any other 
concerns.

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