linux-kernel - Re: [PATCH v5 4/4] platform/x86: Add ACPI i2c-multi-instantiate pseudo driver

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Date:   Thu, 9 Aug 2018 11:59:31 +0200
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Darren Hart <dvhart@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        linux-acpi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        linux-i2c@...r.kernel.org
Subject: Re: [PATCH v5 4/4] platform/x86: Add ACPI i2c-multi-instantiate
 pseudo driver

On Thu, Aug 09, 2018 at 11:15:58AM +0200, Hans de Goede wrote:
> On systems with ACPI instantiated i2c-clients, normally there is 1 fw_node
> per i2c-device and that fw-node contains 1 I2cSerialBus resource for that 1
> i2c-device.
> 
> But in some rare cases the manufacturer has decided to describe multiple
> i2c-devices in a single ACPI fwnode with multiple I2cSerialBus resources.
> 
> An earlier attempt to fix this in the i2c-core resulted in a lot of extra
> code to support this corner-case.
> 
> This commit introduces a new i2c-multi-instantiate driver which fixes this
> in a different way. This new driver can be built as a module which will
> only loaded on affected systems.
> 
> This driver will instantiate a new i2c-client per I2cSerialBus resource,
> using the driver_data from the acpi_device_id it is binding to to tell it
> which chip-type (and optional irq-resource) to use when instantiating.
> 
> Note this driver depends on a platform device being instantiated for the
> ACPI fwnode, see the i2c_multi_instantiate_ids list of ACPI device-ids in
> drivers/acpi/scan.c: acpi_device_enumeration_by_parent().
> 
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>

From my I2C PoV:

Acked-by: Wolfram Sang <wsa@...-dreams.de>


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