Re: [PATCH v3 15/15] media: qcom: camss: Comment CSID dt_id field

Konrad Dybcio
2023-08-28T15:39:06Z

On 28.08.2023 17:34, Bryan O'Donoghue wrote:
> On 26/08/2023 11:18, Konrad Dybcio wrote:
>>> +        /*
>>> +         * A value caled 'CID' gets generated internal to CAMSS logic
>>> +         * which is a concatenation of [vc:6 | dt_id:2] hence we reuse
>>> +         * the least significant two bits of the VC to 'stuff' the CID value.
>>> +         */
>>>           u8 dt_id = vc;
>> And where are you discarding the non-2-lsb?
>
> At the assignment of dt_id
>
> vc:6
> dt_id:2
>
> =>
>
> cid:8 = [vc:6 | dt_id:2]
> vc == 00110110
> cid = [110110 | 10]
>
> I have no more information what CID is or how the bitfield is populated than I have already indicated in the comment/commit log.
>
OK so you're discarding the 2 lsb of the [vc:6|dt_id:2]

however

the way I read the comment would suggest that you're taking
vc[6:2]

Konrad