[linux-sunxi] Re: [PATCH] ARM: dts: sun4i: Add dts file for the pov protab2-ips9 tablet

[Maxime Ripard]

Hi,

On Mon, Sep 07, 2015 at 11:30:03AM +0200, Hans de Goede wrote:
> >>>bma250 already has devicetree support. It is used in Gemei G9
> >>>tablet (sun4i-gemei-g9.dts).
> >>
> >>Yes I've seen that, but does it actually work? I've not tried but
> >>I do not see any compatible string in the actual bma250 code in
> >>the kernel, so I believe that this part of the sun4i-gemei-g9.dts
> >>file does not work ?
> >
> >It worked (even without IRQs) when I submitted the patch. Driver
> >itself is under iio/accel/bma180.c
> 
> That is really weird, because:
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/iio/accel/bma180.c
> 
> Does not have an of_match_table ... ??

Not really, when using DT, i2c will set the i2c_client name to the
device part of the compatible [1] [2], and then if the of_device_id
lookup fails, will fallback to matching the i2c_client name to the
i2c_device_id [3]. Which in our case matches.

Maxime

[1] http://lxr.free-electrons.com/source/drivers/i2c/i2c-core.c#L1281
[2] http://lxr.free-electrons.com/source/drivers/i2c/i2c-core.c#L969
[3] http://lxr.free-electrons.com/source/drivers/i2c/i2c-core.c#L461

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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