Hi Linus,

On Sun, Sep 17, 2017 at 11:38 AM, Linus Walleij
[off-list ref] wrote:

This augments the I2C GPIO driver to use open drain emulation
or hardware support for open drain from the GPIO driver.

This version layers Geert Uytterhoeven's idea to use explicit
sda-gpios and scl-gpios for the GPIO lines, and strongly
encourage the (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) flags to be
used in all device trees.

We have collected ACKs from the ARM SoC maintainers and the
MFD maintainer and are looking for testers to try this out.

Geert Uytterhoeven (1):
  dt-bindings: i2c: i2c-gpio: Add support for named gpios

Linus Walleij (6):
  i2c: gpio: Convert to use descriptors
  gpio: Make it possible for consumers to enforce open drain
  i2c: gpio: Enforce open drain through gpiolib
  i2c: gpio: Augment all boardfiles to use open drain
  i2c: gpio: Local vars in probe
  i2c: gpio: Add support for named gpios in DT

Thanks for doing this, and picking up my patch.

I gave this a try on r8a7740/armadillo800eva.
Without DT changes, the GPIO i2c bus still works fine, but a warning is
printed, as expected:

    gpio-208 (sda): enforced open drain please flag it properly in
DT/ACPI DSDT/board file
    gpio-91 (scl): enforced open drain please flag it properly in
DT/ACPI DSDT/board file

After

    -  sda-gpios = <&pfc 208 GPIO_ACTIVE_HIGH>;
    -  scl-gpios = <&pfc 91 GPIO_ACTIVE_HIGH>;
    + sda-gpios = <&pfc 208 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
    + scl-gpios = <&pfc 91 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;

the warning is gone, and the GPIO i2c bus still works.

Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds