Re: [PATCH v12 net-next 1/9] mfd: ocelot: add helper to get regmap from a resource

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

On Fri, Jul 1, 2022 at 10:35 PM Colin Foster
<colin.foster@xxxxxxxxxxxxxxxx> wrote:
> On Fri, Jul 01, 2022 at 10:23:36PM +0200, Andy Shevchenko wrote:
> > On Fri, Jul 1, 2022 at 9:26 PM Colin Foster
> > <colin.foster@xxxxxxxxxxxxxxxx> wrote:

...

> > > +       res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> > > +       if (res) {
> > > +               regs = devm_ioremap_resource(dev, res);
> > > +               if (IS_ERR(regs))
> > > +                       return ERR_CAST(regs);
> >
> > Why can't it be devm_platform_get_and_ioremap_resource() here?
>
> It can... but it invokes prints of "invalid resource" during
> initialization.
>
> Here it was implied that I should break the function call out:
> https://patchwork.kernel.org/project/netdevbpf/patch/20220628081709.829811-2-colin.foster@xxxxxxxxxxxxxxxx/#24917551

Perhaps a comment in the code, so nobody will try to optimize this in
the future.

> > > +               return devm_regmap_init_mmio(dev, regs, config);
> > > +       }

...

> > > +       return (map) ? map : ERR_PTR(-ENOENT);
> >
> > Too many parentheses.
> >
> > Also you may use short form of ternary operator:
> >
> >        return map ?: ERR_PTR(-ENOENT);
>
> Agreed, and I didn't know about that operator. When Vladimir suggested
> it I thought it was a typo. I should've known better.

It's easy to remember by thinking of

"X ?: Y" as "X _or_ Y".

-- 
With Best Regards,
Andy Shevchenko