Hi,
On 07-09-15 22:52, Maxime Ripard wrote:
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
Hmm, not sure whether that is a useful feature or an ugly hack :)
It is sorta unexpected either way. But I can make good use of this to
enable the accelerometer and maybe also some touchscreens on a bunch of
boards I have.
Still should we rely on this? This means relying on Linux kernel behavior,
rather then something documented in Documentation/devicetree/bindings/...
Regards,
Hans
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