Re: [PATCH v5 2/2] media: i2c: add Himax HM1246 image sensor driver

[Tarang Raval]

Hi Andy,

> > +static inline struct hm1246 *to_hm1246(struct v4l2_subdev *sd)
> > +{
> > +     return container_of_const(sd, struct hm1246, sd);
>
> It's unclear and confusing that _const() variant is used here.
> Either const qualifier is missed somewhere, or _const is redundant.

The use of container_of_const() here is intentional and follows the direction 
taken across multiple recent sensor drivers suggested by Sakari. 
(e.g. ov2735, vd56g3, vd55g1, ov64a40, imx283).

AFAIK, using container_of_const() is a no-op for non-const 
arguments, but keeps the helper type-safe and future-proof against 
possible changes in the V4L2 API. This also maintains consistency with 
other upstream drivers and avoids subtle warnings if any of the subdev 
Callbacks later become const-qualified.

But yes, I guess Sakari can give you a better answer.

Best Regards,
Tarang