Re: [PATCH v4 2/2] phy: qcom-mipi-csi2: Add a CSI2 MIPI DPHY driver

[Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>]

On 3/19/26 15:17, Bryan O'Donoghue wrote:
> On 19/03/2026 13:08, Vladimir Zapolskiy wrote:
>>> Why do you want a media driver? Isn't PHY driver enough?
>>>
>> As for today CAMSS CSIPHY are already media devices, and a user applies media
>> specific properties to them, for instance media bus format, resolution etc.
>> Technically this might be removed from CAMSS, but if so, then it should be
>> done before this new PHY driver model is applied.
>>
>> --
>> Best wishes,
> 
> There's no reason to remove that from CAMSS - it would be an ABI break
> in user-space anyway.

If technically CAMSS CSIPHY could be excluded from the list of CAMSS media
subdevices, then for the sake of simplification it should be done for all
supported platforms in advance, such a change will be independent from this
particular phy series, and vice versa, this CAMSS only driver change will
prepare a ground for media-less CAMSS CSIPHY device drivers, hence it shall
precede this particular CAMSS CSIPHY series.

For backward compatibility with userspace a noop stub will be good enough,
it's not an issue at all.

> The media entity in CAMSS msm_csiphyX handles format negotiation and
> pipeline routing. The PHY driver handles electrical configuration. They
> don't conflict and there multiple cited examples of this upstream already.
> 

-- 
Best wishes,
Vladimir