Re: [PATCH v4 2/2] i2c: add ACPI support for I2C mux ports

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Fri, Oct 23, 2015 at 04:13:11PM +0300, Mika Westerberg wrote:
> On Fri, Oct 23, 2015 at 12:16:11PM +0200, Wolfram Sang wrote:
> > On Fri, Oct 23, 2015 at 11:40:13AM +0300, Mika Westerberg wrote:
> > > On Thu, Oct 22, 2015 at 02:17:42AM -0700, Dustin Byford wrote:
> > > > Although I2C mux devices are easily enumerated using ACPI (_HID/_CID or
> > > > device property compatible string match), enumerating I2C client devices
> > > > connected through an I2C mux needs a little extra work.
> > > > 
> > > > This change implements a method for describing an I2C device hierarchy that
> > > > includes mux devices by using an ACPI Device() for each mux channel along
> > > > with an _ADR to set the channel number for the device.  See
> > > > Documentation/acpi/i2c-muxes.txt for a simple example.
> > > > 
> > > > To make this work the ismt, i801, and designware pci/platform devs now
> > > > share an ACPI companion with their I2C adapter dev similar to how it's done
> > > > in OF.  This is done on the assumption that power management functions will
> > > > not be called directly on the I2C dev that is sharing the ACPI node.
> > > > 
> > > > Signed-off-by: Dustin Byford <dustin@cumulusnetworks.com>
> > > 
> > > This looks good to me.
> > > 
> > > You did also some stylistic changes to the drivers in question which I
> > > think should be placed to a separate patches.
> > 
> > I am fine with those.
> > 
> > > Regardless of that,
> > > 
> > > Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > 
> > I would love to get a Tested-by for the designware part. Then, I could
> > queue it for 4.4 already.
> 
> Tested on Intel Baytrail and Skylake and the existing I2C devices
> (touchpad, touchscreen) still work so for the designware part you can
> also add my,
> 
> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Ah, forgot to mention that the i2c-designware-pcidrv.c misses include of
<linux/acpi.h> so that needs to be fixed. Otherwise we get:

drivers/i2c/busses/i2c-designware-pcidrv.c: In function ‘i2c_dw_pci_probe’:
drivers/i2c/busses/i2c-designware-pcidrv.c:259:2: error: implicit declaration of function ‘ACPI_COMPANION_SET’ [-Werror=implicit-function-declaration]
drivers/i2c/busses/i2c-designware-pcidrv.c:259:33: error: implicit declaration of function ‘ACPI_COMPANION’ [-Werror=implicit-function-declaration]