linux-kernel - Re: [PATCH] pinctrl: gpio: vt8500: Add pin control driver for Wondermedia SoCs

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Message-ID: <1360967181.24923.3.camel@gitbox>
Date:	Sat, 16 Feb 2013 11:26:21 +1300
From:	Tony Prisk <linux@...sktech.co.nz>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	grant.likely@...retlab.ca
Subject: Re: [PATCH] pinctrl: gpio: vt8500: Add pin control driver for
 Wondermedia SoCs

On Fri, 2013-02-15 at 21:27 +0100, Linus Walleij wrote:
> On Fri, Feb 15, 2013 at 3:48 AM, Tony Prisk <linux@...sktech.co.nz> wrote:
> 
> Hm some of these remarks would apply to the BCM2835 driver as
> well, I missed to complain at the time it was added. Probably I was
> all too excited about the new Raspberry.
> 
> Mainly you want Stephens review on this since he wrote the
> driver you based it on...
> 
> > +++ b/arch/arm/Kconfig
> > @@ -1618,10 +1618,10 @@ config LOCAL_TIMERS
> >  config ARCH_NR_GPIO
> >         int
> >         default 1024 if ARCH_SHMOBILE || ARCH_TEGRA
> > +       default 512 if SOC_OMAP5
> >         default 355 if ARCH_U8500
> > +       default 352 if ARCH_VT8500
> >         default 264 if MACH_H4700
> > -       default 512 if SOC_OMAP5
> > -       default 288 if ARCH_VT8500
> >         default 0
> 
> This seems like a totally unrelated chunk, put that in some
> other patch and send off to the ARM SoC people if you want
> it changed.
> 
> > +obj-$(CONFIG_PINCTRL_WMT)      += pinctrl-wmt.o
> > +obj-$(CONFIG_PINCTRL_WM8850)   += pinctrl-wm8850.o
> 
> So one front-end driver and one pluggable SoC-driver
> I guess.
> 
> > +++ b/drivers/pinctrl/pinctrl-wm8850.c
> (skipping this file, looks like OK and pure data)
> 
> > +++ b/drivers/pinctrl/pinctrl-wmt.c
> (...)
> > +#define WMT_PINCONF_PACK(__param, __arg)       ((__param << 16) | __arg)
> > +#define WMT_PINCONF_UNPACK_PARAM(__conf)       (__conf >> 16)
> > +#define WMT_PINCONF_UNPACK_ARG(__conf)         (__conf & 0xffff)
> 
> Please use the generic pinconf helper library, there are no magic
> configurations in this driver. Look at other drivers using generic pinconf
> and get pack/unpack for free and tested.
> 
> (then follows a large block of nice, clean code)
> 
> > +static int wmt_pinconf_set(struct pinctrl_dev *pctldev, unsigned pin,
> > +                          unsigned long config)
> > +{
> > +       struct wmt_pinctrl_data *data = pinctrl_dev_get_drvdata(pctldev);
> > +       enum wmt_pinconf_param param = WMT_PINCONF_UNPACK_PARAM(config);
> > +       u16 arg = WMT_PINCONF_UNPACK_ARG(config);
> > +       u32 bank = pin >> 5;
> > +       u32 bit = pin & 0x1f;
> 
> Comment the two lines above. What kind of magic is happening?
> I can guess, but it's better if it's stated.
> 
> (...)
> > +static int wmt_gpio_get_value(struct gpio_chip *chip, unsigned offset)
> > +{
> > +       struct wmt_pinctrl_data *data = dev_get_drvdata(chip->dev);
> > +       u32 bank = offset >> 5;
> > +       u32 bit = offset & 0x1f;
> 
> Hm it looks like duplicated code as well. What abot a small
> static inline helper function to do the magic?
> 
> > +int wmt_pinctrl_probe(struct platform_device *pdev,
> > +                     struct wmt_pinctrl_data *data)
> > +{
> > +       int err;
> > +       wmt_desc.pins = data->pins;
> > +       wmt_desc.npins = data->npins;
> > +
> > +       data->gpio_chip = wmt_gpio_chip;
> > +       data->gpio_chip.dev = &pdev->dev;
> > +       data->gpio_chip.of_node = pdev->dev.of_node;
> > +       data->gpio_chip.ngpio = data->nbanks * 32;
> > +
> > +       platform_set_drvdata(pdev, data);
> > +
> > +       data->dev = &pdev->dev;
> > +       data->pctl_dev = pinctrl_register(&wmt_desc, &pdev->dev, data);
> > +       if (IS_ERR(data->pctl_dev)) {
> > +               dev_err(&pdev->dev, "Failed to register pinctrl\n");
> > +               return -EINVAL;
> > +       }
> > +
> > +       err = gpiochip_add(&data->gpio_chip);
> > +       if (err) {
> > +               dev_err(&pdev->dev, "could not add GPIO chip\n");
> > +               return err;
> > +       }
> 
> Nice with gpiochip and pinctrl in the same probe, just as
> it should be.
> 
> > +
> > +       data->gpio_range = wmt_pinctrl_gpio_range;
> > +
> > +       data->gpio_range.gc = &data->gpio_chip;
> > +       data->gpio_range.base = data->gpio_chip.base;
> > +       data->gpio_range.npins = data->nbanks * 32;
> > +       pinctrl_add_gpio_range(data->pctl_dev, &data->gpio_range);
> 
> Don't do this. Register ranges from the gpiochip side instead
> of from the pinctrl side of things. This way of doing things is
> deprecated.
> 
> Grep for gpiochip_add_pin_range for examples.
> 
> When you have this right I guess you could probably
> patch the BCM driver as well since it's so similar.
> 
> > +       dev_info(&pdev->dev, "Pin controller initialized\n");
> > +
> > +       return 0;
> > +}
> 
> (...)
> > +++ b/drivers/pinctrl/pinctrl-wmt.h
> 
> Looks OK.
> 
> Yours,
> Linus Walleij

Thanks for the review.

Re: the Kconfig change for increasing the number of GPIO's - I know this
is out of place, but it was easier to just diff all the changes and sort
out the correct patches later.

I just wanted to get a feel for any problems around the main driver
before I started typing in lines and lines of data... only to be told
the data was bad and needed to be changed :)

Thanks again

Regards
Tony Prisk

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