Re: [PATCH v8 04/10] reset: eyeq5: add platform driver

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Wed, Feb 28, 2024 at 06:04:47PM +0100, Théo Lebrun wrote:
> On Tue Feb 27, 2024 at 6:27 PM CET, Andy Shevchenko wrote:
> > On Tue, Feb 27, 2024 at 03:55:25PM +0100, Théo Lebrun wrote:

...

> > > +	u32 offset = id & GENMASK(7, 0);
> > > +	u32 domain = id >> 8;
> >
> > Perhaps
> >
> > 	u32 offset = (id & GENMASK(7, 0)) >> 0;
> > 	u32 domain = (id & GENMASK(31, 8)) >> 8;
> >
> > for better understanding the split?
> 
> Do the additional zero-bit-shift and GENMASK() help understanding? My
> brain needs time to parse them to then notice they do nothing and
> simplify the code in my head, back to the original version.

In my opinion yes, as you exactly showing the split.
But. The better is to use FIELD_GET().

> I personally like the simplest version (the original one). But otherwise
> FIELD_GET() with two globally-defined masks could be a solution as
> well.

Oh, yes, that's what just came to my mind without even looking here.

> I still prefer the original version better. Less symbols, less
> complexity.

[...]

> > > +	priv->rcdev.of_node = np;
> >
> > It's better to use device_set_node().
> 
> I don't see how device_set_node() can help? It works on struct device
> pointers. Here priv->rcdev is a reset_controller_dev struct. There are
> no users of device_set_node() in drivers/reset/.

No users doesn't mean it's good. The API is relatively "new" and takes
care of two things:
1) it uses agnostic interface;
2) it doesn't require any firmware node direct dereference.

The 2) is most important here as allows us to refactor (firmware node) code
in the future.

> > > +	priv->rcdev.of_reset_n_cells = 2;
> > > +	priv->rcdev.of_xlate = eq5r_of_xlate;

However, ideally these should be also translated to use fwnode as IIO did,
for example.

...

> > > +		priv->rcdev.nr_resets += __builtin_popcount(eq5r_valid_masks[i]);
> >
> > Please, use corresponding hweightXX() API.
> 
> Noted. I did not find this keyword even though I searched quite a bit
> for it. "popcount" sounds more logical to me. :-)

Hmm... But it's fundamental, it's called Hamming weight.
https://en.wikipedia.org/wiki/Hamming_weight

-- 
With Best Regards,
Andy Shevchenko