linux-kernel - Re: [PATCH 2/2] mfd: intel-lpss: Add "linux,use-dynamic-adapter-nr" device-prop to i2c-devices

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Message-ID: <20190311191555.4dc2wbwqesqmn2kq@ninjato>
Date:   Mon, 11 Mar 2019 20:15:55 +0100
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Lee Jones <lee.jones@...aro.org>, linux-i2c@...r.kernel.org,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mfd: intel-lpss: Add "linux,use-dynamic-adapter-nr"
 device-prop to i2c-devices

On Mon, Mar 11, 2019 at 12:22:16PM +0100, Hans de Goede wrote:
> The i2c-designware-platdrv assumes that if the pdev has an apci-companion
> it should use a dynamic adapter-nr and otherwise it will use pdev->id as
> adapter-nr.
> 
> On some devices e.g. the Apollo Lake using Acer TravelMate Spin B118,
> some of the LPSS i2c-adapters are enumerated through PCI and do not have
> an ACPI fwnode. These devices are handled as mfd devices so they end up
> using the i2c-designware-platdrv driver.
> 
> This results in the i2c-adapter being registered with the mfd generated
> pdev->id as adapter-nr, which conflicts with existing adapters, triggering
> a WARN(id < 0, "couldn't get idr") in i2c-core-base.c and causing the
> adapter registration to fail.
> 
> To fix this the i2c-designware-platdrv now also supports a
> "linux,use-dynamic-adapter-nr" device-property, which tells it to use a
> dynamic adapter nr even if there is no ACPI fwnode for the device.
> 
> This commit adds this device-property to the properties list for PCI
> enumerated LPSS i2c-adapters.
> 
> BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1687065
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>

You need to CC the devicetree ML on such patches. However, I am afraid I
can pretty much NACK this one already. This is a Linux configuration
item and DT is only for describing HW.

Maybe the designware maintainers have a better idea how to achieve what
you need.


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