Re: [PATCH v5] gpio: pcf857x: Add OF support

[Archit Taneja]

Hi,

On Tuesday 27 August 2013 01:44 PM, Tomasz Figa wrote:
> Hi Laurent,
>
> On Tuesday 27 of August 2013 10:02:39 Laurent Pinchart wrote:
> > Add DT bindings for the pcf857x-compatible chips and parse the device
> > tree node in the driver.
> >
> > Signed-off-by: Laurent Pinchart
> > <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> ---
> >   .../devicetree/bindings/gpio/gpio-pcf857x.txt      | 71
> > ++++++++++++++++++++++ drivers/gpio/gpio-pcf857x.c
> >    | 44 +++++++++++--- 2 files changed, 107 insertions(+), 8
> > deletions(-)
> >   create mode 100644
> > Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt
> >
> > Changes since v4:
> >
> > - Don't try to get ngpio from of_device_id data, we already get it from
> >    i2c_device_id
>
> Hmm, I'm not sure how this is supposed to work.
>
> How does the I2C core resolve OF compatible name to particular entry in
> id_table? I believe it simply passes NULL as the second argument of
> .probe() if the device is instantiated based on OF compatible string and
> not one in the legacy ID table.

It doesn't pass the second argument as NULL. If you look at 
i2c_device_probe() in drivers/i2c/i2c-core.c, the second argument to 
probe is passed as: i2c_match_id(driver->id_table, client)

This will extract the i2c_device_id pointer from the id_table.

Archit

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