linux-kernel - Re: [PATCH v3 4/4] i2c: Add multi-instantiate pseudo driver

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Date:   Wed, 8 Aug 2018 10:08:03 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     John Garry <john.garry@...wei.com>,
        "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>,
        Wolfram Sang <wsa@...-dreams.de>
Cc:     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 v3 4/4] i2c: Add multi-instantiate pseudo driver

Hi,

On 07-08-18 14:46, John Garry wrote:
> On 07/08/2018 09:05, 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>
>> ---
>>  MAINTAINERS                                  |   6 +
>>  drivers/platform/x86/Kconfig                 |  11 ++
>>  drivers/platform/x86/Makefile                |   1 +
>>  drivers/platform/x86/i2c-multi-instantiate.c | 131 +++++++++++++++++++
>>  4 files changed, 149 insertions(+)
>>  create mode 100644 drivers/platform/x86/i2c-multi-instantiate.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 9b377508f24f..09e16d76cab7 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -6657,6 +6657,12 @@ F:    drivers/i2c/i2c-mux.c
>>  F:    drivers/i2c/muxes/
>>  F:    include/linux/i2c-mux.h
>>
>> +I2C MULTI INSTANTIATE DRIVER
>> +M:    Hans de Goede <hdegoede@...hat.com>
>> +L:    linux-i2c@...r.kernel.org
>> +S:    Maintained
>> +F:    drivers/drivers/platform/x86/i2c-multi-instantiate.c
> 
> This path looks incorrect
> 
>> +
>>  I2C MV64XXX MARVELL AND ALLWINNER DRIVER
>>  M:    Gregory CLEMENT <gregory.clement@...tlin.com>
>>  L:    linux-i2c@...r.kernel.org
>> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
>> index 85a93453237c..8256629f58f7 100644
>> --- a/drivers/platform/x86/Kconfig
>> +++ b/drivers/platform/x86/Kconfig
>> @@ -1219,6 +1219,17 @@ config INTEL_CHTDC_TI_PWRBTN
>>        To compile this driver as a module, choose M here: the module
>>        will be called intel_chtdc_ti_pwrbtn.
>>
>> +config I2C_MULTI_INSTANTIATE
>> +    tristate "I2C multi instantiate pseudo device driver"
>> +    depends on I2C && ACPI
>> +    help
>> +      Some ACPI bases systems list multiple i2c-devices in a single ACPI
> 
> I guess that this should be "Some ACPI-based systems"

Thanks, both fixed for v4 of the patchset.

Regards,

Hans


> 
>> +      firmware-node. This driver will instantiate separate i2c-clients
>> +      for each device in the firmware-node.
>> +
>> +      To compile this driver as a module, choose M here: the module
>> +      will be called i2c-multi-instantiate.
>> +
> 
> Thanks,
> John
>