Re: [PATCH v4 1/2] Documentation: Documentation for qcom, llcc

[rishabhb@codeaurora.org]

On 2018-04-16 07:59, Rob Herring wrote:
> On Tue, Apr 10, 2018 at 01:08:12PM -0700, Rishabh Bhatnagar wrote:
>> Documentation for last level cache controller device tree bindings,
>> client bindings usage examples.
> 
> "Documentation: Documentation ..."? That wastes a lot of the subject
> line... The preferred prefix is "dt-bindings: ..."
> 
>> 
>> Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>
>> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
>> ---
>>  .../devicetree/bindings/arm/msm/qcom,llcc.txt      | 58 
>> ++++++++++++++++++++++
>>  1 file changed, 58 insertions(+)
>>  create mode 100644 
>> Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt
>> 
>> diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt 
>> b/Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt
>> new file mode 100644
>> index 0000000..497cf0f
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/msm/qcom,llcc.txt
>> @@ -0,0 +1,58 @@
>> +== Introduction==
>> +
>> +LLCC (Last Level Cache Controller) provides last level of cache 
>> memory in SOC,
>> +that can be shared by multiple clients. Clients here are different 
>> cores in the
>> +SOC, the idea is to minimize the local caches at the clients and 
>> migrate to
>> +common pool of memory
>> +
>> +Properties:
>> +- compatible:
>> +	 Usage: required
>> +	 Value type: <string>
>> +	 Definition: must be "qcom,sdm845-llcc"
>> +
>> +- reg:
>> +	 Usage: required
>> +	 Value Type: <prop-encoded-array>
>> +	 Definition: must be addresses and sizes of the LLCC registers
> 
> How many address ranges?
> 
It consists of just one address range. I'll edit the definition to make
it more clear.
>> +
>> +- #cache-cells:
> 
> This is all written as it is a common binding, but it is not one.
> 
> You already have most of the configuration data for each client in the
> driver, I think I'd just put the client connection there too. Is there
> any variation of this for a given SoC?
> 
#cache-cells and max-slices won't change for a given SOC. So you want me
to hard-code in the driver itself?

>> +	 Usage: required
>> +	 Value Type: <u32>
>> +	 Definition: Number of cache cells, must be 1
>> +
>> +- max-slices:
>> +	 usage: required
>> +	 Value Type: <u32>
>> +	 Definition: Number of cache slices supported by hardware
> 
> What's a slice?
> 
System cache memory provided by LLCC is divided into smaller chunks
called slices. Each slice has its associated size and ID. Clients can
query slice details, activate and deactivate them.
>> +
>> +Example:
>> +
>> +	llcc: qcom,llcc@1100000 {
>> +		compatible = "qcom,sdm845-llcc";
>> +		reg = <0x1100000 0x250000>;
>> +		#cache-cells = <1>;
>> +		max-slices = <32>;
>> +	};
>> +
>> +== Client ==
>> +
>> +Properties:
>> +- cache-slice-names:
>> +	 Usage: required
>> +	 Value type: <stringlist>
>> +	 Definition: A set of names that identify the usecase names of a
>> +			client that uses cache slice. These strings are
>> +			used to look up the cache slice entries by name.
>> +
>> +- cache-slices:
>> +	 Usage: required
>> +	 Value type: <prop-encoded-array>
>> +	 Definition: The tuple has phandle to llcc device as the first
>> +			argument and the second argument is the usecase
>> +			id of the client.
>> +For Example:
>> +	venus {
>> +		cache-slice-names = "vidsc0", "vidsc1";
>> +	 	cache-slices = <&llcc VIDSC0_ID>, <&llcc VIDSC1_ID>;
>> +	};
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>> 
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