Re: [PATCH 2/2] iio: accel: bmc150: Check for a second ACPI device for BOSC0200

[Jonathan Cameron]

On Mon, 4 Dec 2017 11:58:19 +0200
Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote:

> On Sat, Dec 02, 2017 at 12:19:27PM +0000, Jonathan Cameron wrote:
> > On Wed, 29 Nov 2017 22:31:12 +0000
> > Jeremy Cline <jeremy@xxxxxxxxxx> wrote:
> >   
> > > Some BOSC0200 acpi_device-s describe two accelerometers in a single ACPI
> > > device. Check for a companion device and handle a second i2c_client
> > > if it is present.  
> > 
> > + Mika and Wolfram - please cc them on anything odd and i2c / ACPI related.
> > (I like to share the pain)
> > 
> > My usual question, just out of curiosity as we have to cope with this
> > fun anyway.  Are you actually allowed to do this under the ACPI spec
> > or not?  I would assume an acpi device is supposed to be just that A
> > device...  I fall asleep every time I try to read that spec ;)  
> 
> Yes, it is allowed. Typically you have an ACPI device and it can have
> multiple I2cSerialBus() connections.
> 
> Linux ACPI/I2C core then picks the first one and creates i2c_client from
> that but the additional connections need to be created by the driver in
> question.

Why does it not make sense to just create them all from the ACPI/I2C core?

> 
> BTW, there is a function i2c_new_secondary_device() that is supposed to
> be used for this but it does not have ACPI support yet (maybe it is good
> time to add it now, with this patch series?)
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