Re: [PATCH 1/3] phy: core: add generic MIPI C-PHY configuration API

[Bryan O'Donoghue <bod@kernel.org>]

On 19/10/2026 11:24, Bryan O'Donoghue wrote:
> On 18/10/2026 00:00, Bryan O'Donoghue wrote:
>>> +    unsigned int        lanes;
>>
>> This statement and how you go about using the data aren't consistent.
> 
> Re-reading this.
> 
> unsigned int trios; would be fine too => data_lanes and lane_polarities
> is a multiple of trios - always three - does it imply that the first
> three entries in data-lanes == the first trio ?
> 
> Presumably.
> 
> That would work too.
> 
> data-lanes = <4 5 6 1 2 3>;
> 
> =>
> 
> trios = 2
> 
> =>
> 
> data_lanes[4, 5, 6, 1, 2, 3];
> 
> trio[0]:lanes == [4, 5, 6];
> trio[1]:lanes == [1, 2, 3];
> 
> Probably "trios" instead of "lanes" makes more sense here and the driver
> just always validates that count(data_lanes) % 3 is always false.
> 
> ---
> bod

I'm going to argue with myself.

data-lanes = <1>

=>

lanes = 1; // not trios no need to introduce a new term

=>

three pads on the Soc

=>

The question is - is data_lanes required for the CPHY opts struct ? For 
the qcom CAMSS case the answer ~ always no - we will be attaching a 
sensor and will read-back the positions from that endpoint.

It is conceivable that other systems may want to pass data-lanes down to 
the driver because they won't have a media-graph but, I'd say we should 
arbitrate that then - leave it up to someone who needs the fields to add 
them.

=>

lanes // the CSID and PHY should agree
symbol_rate // so both the CSID and phy agree on symbols per second

Remove:

- lane_positions
- lane_polarities

Since at least for this series, they won't be needed.

The CSID still needs to know the number of lanes and how many symbols so 
that it can calculate bandwidth so .... lets just include the data we 
know we need.

struct cphy_opts {lanes; rate/symbols}; dropping lane_positions and 
lane_polarities.

I've no objection to the low-level timing variables myself but OTOH we 
don't require them at this point in time.

Perhaps drop unless/until someone can show a need for them.

Excellent bod, agree with you now.

---
bod