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SubjectRe: [PATCH 1/2] slimbus: ngd: dt-bindings: Add slim ngd dt bindings
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On 23/05/18 20:28, Rob Herring wrote:
> On Wed, May 23, 2018 at 1:11 PM, Srinivas Kandagatla
> <srinivas.kandagatla@linaro.org> wrote:
>>
>>
>> On 23/05/18 17:40, Rob Herring wrote:
>>>>
>>>> +
>>>> +- qcom,ngd-id
>>>> + Usage: required
>>>> + Value type: <u32>
>>>> + Definition: ngd instance id in the controller
>>>
>>> Why do you need this?
>>>
>> Please ignore my comment from previous reply.
>>
>> There are more than one instances of ngd in this slim controller.
>> We need this to make sure we are programming the correct one.
>
> Doesn't the parent-child relationship of devices on the bus provide
> that?
Thanks for the hint, that sounds like the actual problem here,
If I represent the node with proper parent-child relationship like this,
it will remove the need of this property and would work perfectly in
case we want to support multiple ngds in future!

slim@91c0000 {
compatible = "qcom,msm8996-slim";
reg = <0x91c0000 0x2C000>;
interrupts = <0 163 0>;
dmas = <&slimbam 3>, <&slimbam 4>;
dma-names = "rx", "tx";
#address-cells = <1>;
#size-cells = <1>;
ngd@1 {
reg = <1>;
#address-cells = <1>;
#size-cells = <1>;
codec@1 {
compatible = "slim217,1a0";
reg = <1 0>;
};
};
};



If you mean to provide consistent numbering to userspace, then
> that's not a DT problem (nor one that Linux plans to solve).
>
No, this is not problem am trying to solve.

>> We also need this instance ID during powering it up using QMI.
>
> Wouldn't that be a QMI ID?

It is passed as parameter to SLIMBUS_QMI_SELECT_INSTANCE_REQ_V01 request.

thanks,
srini
>
> Rob
>

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