Re: [PATCH v2 2/3] soundwire: SDCA: add helper macro to access controls

[Pierre-Louis Bossart]

Thanks for the review Vinod,

> This is good, thanks for adding it in changelog. Can you also add this
> description to Documentation (that can come as an individual patch),

ok

> > +/*
> > + * v1.2 device - SDCA address mapping
> > + *
> > + * Spec definition
> > + *	Bits		Contents
> > + *	31		0 (required by addressing range)
> > + *	30:26		0b10000 (Control Prefix)
>
> So this is for 30:26

I don't get the comment, sorry.

> > + *	25		0 (Reserved)
> > + *	24:22		Function Number [2:0]
> > + *	21		Entity[6]
> > + *	20:19		Control Selector[5:4]
> > + *	18		0 (Reserved)
> > + *	17:15		Control Number[5:3]
> > + *	14		Next
> > + *	13		MBQ
> > + *	12:7		Entity[5:0]
> > + *	6:3		Control Selector[3:0]
> > + *	2:0		Control Number[2:0]
> > + */
> > +
> > +#define SDW_SDCA_CTL(fun, ent, ctl, ch)						\
> > +	(BIT(30)							|	\
>
> Programmatically this is fine, but then since we are defining for the
> description above, IMO it would actually make sense for this to be defined
> as FIELD_PREP:
>
>          FIELD_PREP(GENMASK(30, 26), 1)
>
> or better
>
>          u32_encode_bits(GENMASK(30, 26), 1)
>
> > +	FIELD_PREP(GENMASK(24, 22), FIELD_GET(GENMASK(2, 0), (fun)))	|	\
>
> Why not use u32_encode_bits(GENMASK(24, 22), (fun)) instead for this and
> below?

Because your comment for the v1 review was to use FIELD_PREP/FIELD_GET, 
and your other patches for bitfield access only use FIELD_PREP/FIELD_GET.

I really don't care about which macro is used but it wouldn't hurt to 
have some level of consistency between different parts of the code? Why 
not use FIELD_PREP/GET everywhere?

> > +	FIELD_PREP(BIT(21), FIELD_GET(BIT(6), (ent)))			|	\
> > +	FIELD_PREP(GENMASK(20, 19), FIELD_GET(GENMASK(5, 4), (ctl)))	|	\
> > +	FIELD_PREP(GENMASK(17, 15), FIELD_GET(GENMASK(5, 3), (ch)))	|	\
> > +	FIELD_PREP(GENMASK(12, 7), FIELD_GET(GENMASK(5, 0), (ent)))	|	\
> > +	FIELD_PREP(GENMASK(6, 3), FIELD_GET(GENMASK(3, 0), (ctl)))	|	\
> > +	FIELD_PREP(GENMASK(2, 0), FIELD_GET(GENMASK(2, 0), (ch))))
>
> Also, can we rather have a nice function for this, that would look much
> cleaner

I am not sure what would be cleaner but fine.

> And while at it, consider defining masks for various fields rather than
> using numbers in GENMASK() above, that would look better, be more
> readable and people can reuse it.

Actually on this one I disagree. These fields are not intended to be 
used by anyone, the goal is precisely to hide them behind regmap, and 
the use of raw numbers makes it easier to cross-check the documentation 
and the code. Adding a separate set of definitions would not increase 
readability.