[PATCH 27/32] gpio: Add support for the FXL6408 GPIO expander.

Eric Anholt eric at anholt.net
Thu Jun 9 10:22:27 PDT 2016

Linus Walleij <linus.walleij at linaro.org> writes:

> On Wed, Jun 1, 2016 at 11:43 PM, Gerd Hoffmann <kraxel at redhat.com> wrote:
>> +#define FXL6408_OUTPUT                 0x05
>> +/* Bits here make the output High-Z, instead of the OUTPUT value. */
>> +#define FXL6408_OUTPUT_HIGH_Z          0x07
> (...)
>> +       /* Disable High-Z of outputs, so that our OUTPUT updates
>> +        * actually take effect.
>> +        */
>> +       i2c_smbus_write_byte_data(client, FXL6408_OUTPUT_HIGH_Z, 0);
> High-Z is probably the same as open drain right? And if not open drain,
> it is push-pull.
> So you want to implement .set_single_ended() for configuring the lines in
> "high-z", i.e. open drain output mode.

I'll keep this in mind for whenever I end up writing my next GPIO
driver, but this one is dead for now (not actually usable because of the
closed firmware).
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