linux-kernel - Re: [PATCH v2 2/2] pinctrl: nuvoton: add NPCM7xx pinctrl and GPIO driver

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Message-ID: <CAP6Zq1iywxS7aMHVWT7N3HFxHR-QOvZ8OEb7hpPkmz55xV56_g@mail.gmail.com>
Date:   Mon, 30 Jul 2018 02:24:00 +0300
From:   Tomer Maimon <tmaimon77@...il.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Avi Fishman <avifishman70@...il.com>,
        Nancy Yuen <yuenn@...gle.com>,
        Brendan Higgins <brendanhiggins@...gle.com>,
        Patrick Venture <venture@...gle.com>,
        Joel Stanley <joel@....id.au>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>
Subject: Re: [PATCH v2 2/2] pinctrl: nuvoton: add NPCM7xx pinctrl and GPIO driver

Hi Linus,

On 30 July 2018 at 00:59, Linus Walleij <linus.walleij@...aro.org> wrote:

> On Thu, Jul 26, 2018 at 2:01 AM Tomer Maimon <tmaimon77@...il.com> wrote:
>
> > I initialize bgpio as follow:
> >
> >                         ret = bgpio_init(&pctrl->gpio_bank[id].gc,
> >                                          pctrl->dev, 4,
> >                                          pctrl->gpio_bank[id].base +
> >                                          NPCM7XX_GP_N_DIN,
> >                                          pctrl->gpio_bank[id].base +
> >                                          NPCM7XX_GP_N_DOUT,
> >                                          NULL,
> >                                          NULL,
> >                                          pctrl->gpio_bank[id].base +
> >                                          NPCM7XX_GP_N_IEM,
> >                                          BGPIOF_READ_OUTPUT_REG_SET);
>
> (...)
> > The problem occur when reading the GPIO value from bgpio_get_set
> function,
> > because the directions value are inverse it reading the wrong I/O
> registers
> >
> > For direction out it reading dat register (instead of set register)
> >
> > For direction in it calling set register (instead of dat register)
>
> Hm I don't quite get it... sorry. Maybe if you show your fix and what
> you expect to happen I can understand better?
>

Of course, in the last patch sent three days a go (V3 -
https://patchwork.ozlabs.org/patch/949942/) I did as follow to workaround
the issue:

       int (*get)(struct gpio_chip *chip, unsigned offset);
       int (*get_multiple)(struct gpio_chip *chip, unsigned long *mask,
                           unsigned long *bits);

......

static int npcmgpio_get_value(struct gpio_chip *chip, unsigned int offset)
{
       struct npcm7xx_gpio *bank = gpiochip_get_data(chip);
       unsigned long tmp_bgpio_dir = bank->gc.bgpio_dir;
       int val;

       /*
        * sets bgpio_dir parameter value to the opposite value
        * for calling the right registers in bgpio_get_set
        * function
        */



*       bank->gc.bgpio_dir = ~bank->gc.bgpio_dir;       val =
bank->get(chip, offset);       bank->gc.bgpio_dir = tmp_bgpio_dir;*
       return val;
}

static int npcmgpio_get_multiple_value(struct gpio_chip *chip,
                                      unsigned long *mask, unsigned long
*bits)
{
       struct npcm7xx_gpio *bank = gpiochip_get_data(chip);
       unsigned long tmp_bgpio_dir = bank->gc.bgpio_dir;
       int val;

       /*
        * sets bgpio_dir parameter value to the opposite value
        * for calling the right registers in bgpio_get_set_multiple
        * function
        */



*       bank->gc.bgpio_dir = ~bank->gc.bgpio_dir;       val =
bank->get_multiple(chip, mask, bits);       bank->gc.bgpio_dir =
tmp_bgpio_dir;*
       return val;
}

......

       pctrl->gpio_bank[id].get = pctrl->gpio_bank[id].gc.get;
       pctrl->gpio_bank[id].gc.get = npcmgpio_get_value;
       pctrl->gpio_bank[id].get_multiple = ptrl->gpio_bank[id].gc.get_mul
tiple;
       pctrl->gpio_bank[id].gc.get_multiple = npcmgpio_get_multiple_value;


but it is not that good solution, because the bold commands are not atomic
(locked) operations.


>
> Do you mean that because you write the inverse value to
> IEM this happens, and the BGPIO code assumes that
> you always write 1 to set a line as input and 0 to set it
> as output?
>

yes, because of it the bgpio_get_set and bgpio_get_set_multiple setting the
opposite data registers .


>
> I would say if this causes the problem we should just add
> a new BGPIOF_INVERTED_REG_DIR with comment in
> include/linux/gpio/driver.h and make the necessary fix to
> respect this flag in the gpio-mmio.c core so it works right.
>
> If you do this as a separate patch I would be grateful :)
>

Sure, I will send a separate patch later on to overcome it.

>
> Yours,
> Linus Walleij
>

Thanks,

Tomer

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