Re: [PATCH v1 12/16] pinctrl: starfive: Add pinctrl driver for StarFive SoCs

Andy Shevchenko
2021-10-18T16:24:21Z

On Mon, Oct 18, 2021 at 6:56 PM Emil Renner Berthing <kernel@esmil.dk> wrote:
> On Mon, 18 Oct 2021 at 17:48, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> > On Mon, Oct 18, 2021 at 6:35 PM Emil Renner Berthing <kernel@esmil.dk> wrote:
> > > On Tue, 12 Oct 2021 at 19:03, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> > > > On Tue, Oct 12, 2021 at 4:43 PM Emil Renner Berthing <kernel@esmil.dk> wrote:

...

> > > > > + case PIN_CONFIG_BIAS_DISABLE:
> > > >
> > > > > + mask |= PAD_BIAS_MASK;
> > > >
> > > > Use it...
> > > >
> > > > > + value = (value & ~PAD_BIAS_MASK) | PAD_BIAS_DISABLE;
> > > >
> > > > ...here. Ditto for the similar cases in this function and elsewhere.
> > >
> > > I don't follow. How do you want me to use mask? If I did value =
> > > (value & ~mask) | PAD_BIAS_DISABLE; then I'd wipe the previous
> > > configuration. Eg. suppose the first config is the drive strength and
> > > second disables bias. Then on the 2nd loop mask =
> > > PAD_DRIVE_STRENGTH_MASK | PAD_BIAS_MASK and the drive strength value
> > > would be wiped.
> >
> > Collect masks and new values in temporary variables and apply them
> > once after the loop is done, no?
>
> But that's exactly what the code does. It merges all the config
> options into a single mask and value so we only need to do rmw on the
> register once.

Then masking the value makes no sense.
What you should have is simply as

mask |= FOO;
value |= BAR;

...

> > > > > + ret = clk_prepare_enable(clk);
> > > > > + if (ret) {
> > > >
> > > > > + reset_control_deassert(rst);
> > > >
> > > > Use devm_add_action_or_reset().
> > >
> > > I don't see how that is better.
> >
> > Pity. The rule of thumb is to either try to use devm_*() everywhere in
> > the probe, or don't use it at all. Above is the more-or-less standard
> > pattern where devn_add_action_or_reset() is being used in the entire
> > kernel.
> >
> > > Then I'd first need to call that and
> > > check for errors, but just on the line below enabling the clock the
> > > reset line is deasserted anyway, so then the action isn't needed any
> > > longer. So that 3 lines of code for devm_add_action_or_reset +
> > > lingering unneeded action or code to remove it again vs. just the line
> > > above.
> >
> > Then don't use devm_*() at all. What's the point?
>
> I'm confused. So you wan't an unneeded action to linger because the
> probe function temporarily asserts reset for 3 lines of code?

I;m talking about clk_prepare_enable().

...

> > > > > + sfp->gc.of_node = dev->of_node;
> > > >
> > > > Isn't GPIO library do this for you?
> > >
> > > If it does I can't find it.
> >
> > Heh... `man git grep`
> > Hint: `git grep -n 'of_node = .*of_node' -- drivers/gpio/gpiolib*`
>
> That's exactly what I did.

Now look at the result and find the correct place where it's done.
Btw, all hits are in the very same function.

--
With Best Regards,
Andy Shevchenko