Re: [PATCH v8 3/9] mfd: madera: Add common support for Cirrus Logic Madera codecs

[Richard Fitzgerald]

On 26/02/18 14:11, Andy Shevchenko wrote:
> On Mon, Feb 26, 2018 at 3:05 PM, Richard Fitzgerald
> <rf@xxxxxxxxxxxxxxxxxxxxx> wrote:
> > This adds the generic core support for Cirrus Logic "Madera" class codecs.
> > These are complex audio codec SoCs with a variety of digital and analogue
> > I/O, onboard audio processing and DSPs, and other features.
> >
> > These codecs are all based off a common set of hardware IP so can be
> > supported by a core of common code (with a few minor device-to-device
> > variations).
>
>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by the
> > + * Free Software Foundation; version 2.
>
> This is redundant.

Ditto my other reply. Our legal team want these lines.

> > +static void madera_enable_hard_reset(struct madera *madera)
> > +{
> > +       if (madera->reset_gpio)
>
> if (!...)
>   return

Could do but why bother? For such a trivial function, in my opinion

static void madera_enable_hard_reset(struct madera *madera)
{
	if (madera->reset_gpio)
		gpiod_set_value_cansleep(madera->reset_gpio, 0);
}

is simpler and more readable than

static void madera_enable_hard_reset(struct madera *madera)
{
	if (!madera->reset_gpio)
		return;

	gpiod_set_value_cansleep(madera->reset_gpio, 0);
}

> > +               gpiod_set_value_cansleep(madera->reset_gpio, 0);
> > +}
> > +
> > +static void madera_disable_hard_reset(struct madera *madera)
> > +{
> > +       if (madera->reset_gpio) {
>
> Ditto.

As above, yes it would work the other way but I think for such a simple
implementation the way I have written it is more readable.

> > +               gpiod_set_value_cansleep(madera->reset_gpio, 1);
> > +               usleep_range(1000, 2000);
> > +       }
> > +}
> > +
>
> > +#ifdef CONFIG_PM
>
> __maybe_unused
>
>
> > +const struct dev_pm_ops madera_pm_ops = {
> > +       SET_RUNTIME_PM_OPS(madera_runtime_suspend,
> > +                          madera_runtime_resume,
> > +                          NULL)
> > +};
>
> There is a macro helper for this I believe.

Not for a dev_pm_ops that only has runtime pm.
If you're thinking of UNIVERSAL_DEV_PM_OPS that would set the same
functions as handlers for system suspend, which we don't want to do
for the reasons given in the comment describing UNIVERSAL_DEV_PM_OPS.

> > +const struct of_device_id madera_of_match[] = {
> > +       { .compatible = "cirrus,cs47l35", .data = (void *)CS47L35 },
> > +       { .compatible = "cirrus,cs47l85", .data = (void *)CS47L85 },
> > +       { .compatible = "cirrus,cs47l90", .data = (void *)CS47L90 },
> > +       { .compatible = "cirrus,cs47l91", .data = (void *)CS47L91 },
> > +       { .compatible = "cirrus,wm1840", .data = (void *)WM1840 },
>
> > +       {},
>
> No comma.

Seems to be personal preference. Both ways are used in the kernel and
we've always used this style so I'll leave it to Lee to decide.

> > +};
>
>
> > +               ret = devm_gpio_request_one(madera->dev,
> > +                                           madera->pdata.reset,
> > +                                           GPIOF_DIR_OUT | GPIOF_INIT_LOW,
> > +                                           "madera reset");
> > +               if (!ret)
> > +                       madera->reset_gpio = gpio_to_desc(madera->pdata.reset);
>
> Why? What's wrong with descriptors?

This is what I mean by code going stale when it's acked but then never
gets merged. Some time ago there was a reason (which I forget).

> > +       dev_set_drvdata(madera->dev, madera);
> ...
> > +       if (dev_get_platdata(madera->dev))
>
> What this dance for?

Are you perhaps thinking the second line is dev_get_drvdata()?
dev_get_platdata() gets a pointer to any pdata, so not related
to dev_set_drvdata().

> > +       ret = mfd_add_devices(madera->dev, PLATFORM_DEVID_NONE,
> > +                             mfd_devs, n_devs,
> > +                             NULL, 0, NULL);
>
> devm_?

I can try it and see. It's scary because we can depend on our
children but maybe devm_mfd_add_devices() is safe.

> > +       if (i2c->dev.of_node) {
> > +               of_id = of_match_device(madera_of_match, &i2c->dev);
> > +               if (of_id)
> > +                       type = (unsigned long)of_id->data;
> > +       } else {
> > +               type = id->driver_data;
> > +       }
>
> > +       if (spi->dev.of_node) {
> > +               of_id = of_match_device(madera_of_match, &spi->dev);
> > +               if (of_id)
> > +                       type = (unsigned long)of_id->data;
>
> There is a helper to get match data.
>
> > +       } else {
> > +               type = id->driver_data;
> > +       }
>
> > +struct madera_irqchip_pdata;
> > +struct madera_codec_pdata;
>
>
> Why do you need platform data in new code?

Answered in a comment in another patch. We care about allowing people
to use our chips with systems that don't use devicetree/acpi. There
are also many out-of-tree systems.

> > + * @reset:         GPIO controlling /RESET (0 = none)
>
> Shouldn't be descriptor?