[PATCH] arm: gpio: Add set_flags callback to the Tegra gpio driver

[Łukasz Majewski]

Hi Svyatoslav,

> пт, 19 вер. 2025 р. о 13:11 Lukasz Majewski <lukma at nabladev.com> пише:
> >
> > In some Tegra SoC (like e.g. T30) there is a possibility that one
> > will configure at early boot state a pin as GPIO (to use it for
> > e.g. carrier board detection). However, afterwards (i.e. in Linux)
> > the same pin will be used as the special function one.
> >
> > Current Tegra gpio driver doesn't allow this, so callback for
> > set_flags() has been defined to properly setup the GPIO when
> > required.  
> 
> Please write the commit message in the imperative mood.
> 
> > For now following flags are supported:
> > - GPIOD_IS_AF (i.e. "alternate function").
> > - GPIOD_IS_IN
> > - GPIOD_IS_OUT
> >
> > In long term the tegra_gpio_set_flags() is going to replace
> > direction_{input|output} callbacks.
> >  
> 
> It is not a book chapter, describe what the commit does briefly.

Sorry, but the commit message is a pretty nice form of the
documentation.

For example when you come back to a project, after a few years each
extra sentence is priceless.

> 
> > Signed-off-by: Lukasz Majewski <lukma at nabladev.com>
> > ---
> >  drivers/gpio/tegra_gpio.c | 24 ++++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> >
> > diff --git a/drivers/gpio/tegra_gpio.c b/drivers/gpio/tegra_gpio.c
> > index 3d1e18854f2..1e8bd051875 100644
> > --- a/drivers/gpio/tegra_gpio.c
> > +++ b/drivers/gpio/tegra_gpio.c
> > @@ -258,6 +258,29 @@ static int tegra_gpio_rfree(struct udevice
> > *dev, unsigned int offset) return 0;
> >  }
> >
> > +static int tegra_gpio_set_flags(struct udevice *dev, unsigned int
> > offset,
> > +                               ulong flags)
> > +{
> > +       struct tegra_port_info *state = dev_get_priv(dev);
> > +       int gpio = state->base_gpio + offset;
> > +
> > +       debug("gpio_set_flags: pin = %d (port %d:bit %d), flag =
> > %d\n",
> > +             gpio, GPIO_FULLPORT(gpio), GPIO_BIT(gpio), flags);
> > +  
> 
> Have you even built this code yourself? "flags" is of type ulong, not
> int

It was compiling, but I will double check it. 

> 
> > +       if (flags & GPIOD_IS_AF) {
> > +               set_config(gpio, CFG_SFIO);
> > +               return 0;
> > +       } else if (flags & GPIOD_IS_IN) {
> > +               return tegra_gpio_direction_input(dev, offset);
> > +       } else if (flags & GPIOD_IS_OUT) {
> > +               bool value = flags & GPIOD_IS_OUT_ACTIVE;
> > +
> > +               return tegra_gpio_direction_output(dev, offset,
> > value);
> > +       }
> > +
> > +       return -EINVAL;
> > +}
> > +
> >  static const struct dm_gpio_ops gpio_tegra_ops = {
> >         .direction_input        = tegra_gpio_direction_input,
> >         .direction_output       = tegra_gpio_direction_output,
> > @@ -266,6 +289,7 @@ static const struct dm_gpio_ops gpio_tegra_ops
> > = { .get_function           = tegra_gpio_get_function,
> >         .xlate                  = tegra_gpio_xlate,
> >         .rfree                  = tegra_gpio_rfree,
> > +       .set_flags              = tegra_gpio_set_flags,  
> 
> If you are already touching this anyway, then touch it properly. Since
> set_flags op is meant to remove direction ops, then remove latter too.
> 

Ok.

> >  };
> >
> >  /*
> > --
> > 2.39.5
> >  
> 
> This commit causes regression on LG P990 board, backlight is located
> on gpio i2c line and with this patch gpio i2c refuses to work
> 
> (bootloader) Core:  114 devices, 27 uclasses, devicetree: separate
> (bootloader) MMC:   sdhci at c8000400: 1, sdhci at c8000600: 0
> (bootloader) Loading Environment from MMC... Reading from MMC(0)...
> *** (bootloader) Warning - bad CRC, using default environment
> (bootloader)
> (bootloader) Can't get i2c-5 gpios! Error: -22
> (bootloader) Can't get i2c-5 gpios! Error: -16
> (bootloader) In:    serial,usbkbd,button-kbd
> (bootloader) Out:   serial,vidconsole
> (bootloader) Err:   serial,vidconsole
> (bootloader) Net:   No ethernet found.
> (bootloader)
> (bootloader) Autoboot in 0 seconds

Apparently, some flags are not yet supported - like  GPIOD_PULL_UP/DOWN
or GPIOD_OPEN_DRAIN.

Is this the one from u-boot/board/lg/star/star.c function
star_fix_panel()?

Or is it somewhere else - for example in drivers/i2c/i2c-gpio.c ?

For the latter it looks like I do support all the required flags.

At least on my Colibri T30 it works correctly - so extra help is
appreciated.

-- 
Best regards,

Lukasz Majewski

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