linux-kernel - Re: [RFC v2 1/1] i2c: acpi: scan ACPI enumerated I2C mux channels

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Message-ID: <20151009214241.GC1481@katana>
Date:	Fri, 9 Oct 2015 22:42:44 +0100
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Dustin Byford <dustin@...ulusnetworks.com>
Cc:	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	rjw@...ysocki.net, linux-acpi@...r.kernel.org
Subject: Re: [RFC v2 1/1] i2c: acpi: scan ACPI enumerated I2C mux channels

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 <dustin@...ulusnetworks.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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