On Fri, Aug 14, 2015 at 12:31:33PM -0700, Dustin Byford wrote:
> 
> Set an ACPI companion for I2C mux channels enumerated through ACPI and
> ensure they are scanned for devices.
> 
> Signed-off-by: Dustin Byford <dus...@cumulusnetworks.com>

Mika, is this one okay with you?

> ---
>  drivers/i2c/i2c-core.c | 10 ++++++++++
>  drivers/i2c/i2c-mux.c  |  8 ++++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index c83e4d1..23cc8e9 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -171,8 +171,18 @@ static void acpi_i2c_register_devices(struct i2c_adapter 
> *adap)
>       if (!adap->dev.parent)
>               return;
>  
> +     /*
> +      * Determine where to start walking the ACPI namespace.  The common
> +      * case is to start at the adapter's parent device.  However, in
> +      * the case of a "virtual" I2C adapter created to represent a mux
> +      * channel the parent dev (pointing to the mux device) does not
> +      * have an ACPI handle.  Walk starting at the adapter instead.
> +      */
>       handle = ACPI_HANDLE(adap->dev.parent);
>       if (!handle)
> +             handle = ACPI_HANDLE(&adap->dev);
> +
> +     if (!handle)
>               return;
>  
>       status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
> diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
> index 2ba7c0f..2731b99 100644
> --- a/drivers/i2c/i2c-mux.c
> +++ b/drivers/i2c/i2c-mux.c
> @@ -25,6 +25,7 @@
>  #include <linux/i2c.h>
>  #include <linux/i2c-mux.h>
>  #include <linux/of.h>
> +#include <linux/acpi.h>
>  
>  /* multiplexer per channel data */
>  struct i2c_mux_priv {
> @@ -173,6 +174,13 @@ struct i2c_adapter *i2c_add_mux_adapter(struct 
> i2c_adapter *parent,
>               }
>       }
>  
> +     /*
> +      * Now try to populate the mux adapter's ACPI node.
> +      */
> +     if (has_acpi_companion(mux_dev))
> +             acpi_preset_companion(&priv->adap.dev, ACPI_COMPANION(mux_dev),
> +                                   chan_id);
> +
>       if (force_nr) {
>               priv->adap.nr = force_nr;
>               ret = i2c_add_numbered_adapter(&priv->adap);
> -- 
> 2.1.4
> 

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