Grant Likely wrote:

This looks pretty good to me.  The documentation format isn't strict,
just follow the pattern seen in other bindings.  Make sure you post
new bindings to devicetree-discuss@lists.ozlabs.org for review.  A
couple of comments below.

Ok. I know it now for the next time :)

quoted

Documentation/powerpc/dts-bindings/gpio/i2c.txt

GPIO-based I2C

Required properties:
- compatible : should be "virtual,i2c-gpio".
- gpios : should specify GPIOs used for SDA and SCL lines, in that order.
- sda-is-open-drain : should be non-zero if SDA gpio is open-drain.
- sda-enforce-dir : should be non-zero if SDA gpio must be configured for
                   input before reading and for output before writing.
- scl-is-open-drain : should be non-zero if SCL gpio is open-drain.
- scl-is-output-only : should be non-zero if SCL is an output gpio only.

Instead of looking for a value in these properties, just make them
empty properties and change behaviour based on whether or not the
property is present.

It seems reasonable. Thanks.

Why is the scl-is-output-only property needed?

It is needed to specify that the I2C master can't honour clock stretching done by I2C slave devices, as it cannot read back SCL.

quoted

- udelay : signal toggle delay. SCL frequency is (500 / udelay) kHz

You should follow the lead of
Documentation/powerpc/dts-bindings/fsl/i2c.txt here and specify a
clock-frequency property.

Ok.

quoted

- timeout : clock stretching timeout in milliseconds.

I don't understand what this property means.

It is the maximum time that the I2C master should wait for SCL to go high when a I2C slave is "clock-stretching".

Cheers,
Albert