linux-kernel - Re: [PATCH v3 2/4] ACPI / scan: Create platform device for fwnodes with multiple i2c devices

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Message-ID: <13770931-2322-96a3-1667-83c96b25bcfb@redhat.com>
Date:   Tue, 7 Aug 2018 13:29:33 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        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>,
        John Garry <john.garry@...wei.com>, linux-i2c@...r.kernel.org
Subject: Re: [PATCH v3 2/4] ACPI / scan: Create platform device for fwnodes
 with multiple i2c devices

Hi,

On 07-08-18 13:19, Andy Shevchenko wrote:
> On Tue, 2018-08-07 at 10:05 +0200, Hans de Goede wrote:
>> Some devices have multiple I2cSerialBus resources and for things to
>> work
>> an i2c-client must be instantiated for each, each with its own
>> i2c_device_id.
>>
>> Normally we only instantiate an i2c-client for the first resource,
>> using
>> the ACPI HID as id.
>>
>> This commit adds a list of HIDs of devices, which need multiple i2c-
>> clients
>> instantiated from a single fwnode, to
>> acpi_device_enumeration_by_parent and
>> makes acpi_device_enumeration_by_parent return false for these devices
>> so
>> that a platform device will be instantiated.
>>
>> This allows the drivers/platform/x86/i2c-multi-instantiate.c driver,
>> which
>> knows which i2c_device_id to use for each resource, to bind to the
>> fwnode
>> and initiate an i2c-client for each resource.
>>
> 
>> +	/*
>> +	 * These devices have multiple I2cSerialBus resources and an
>> i2c-client
>> +	 * must be instantiated for each, each with its own
>> i2c_device_id.
>> +	 * Normally we only instantiate an i2c-client for the first
>> resource,
>> +	 * using the ACPI HID as id. These special cases are handled by
>> the
>> +	 * drivers/platform/x86/i2c-multi-instantiate.c driver, which
>> knows
>> +	 * which i2c_device_id to use for each resource.
>> +	 */
>> +	static const struct acpi_device_id i2c_multi_instantiate_ids[] =
>> {
>> +		{"BSG1160", 0},
>> +		{"", 0},
>> +	};
> 
> Style nits:
> - can we move it outside of function?

Sure, but there are 2 existing users of an array of acpi_device_id-s
combined with an acpi_match_device_ids() call and both have the array
inside the function, so for consistency it seems better to keep it
where it is.

> - terminator better without comma

Agreed, will fix for v4.

> - is this existing style in the file and / or files in this folder for
> IDs? (I mean unnecessary 0:s and empty string?

It seems that all variants one can come up with are already used inside
this single file.

I agree that less is more, so I will change this to:

         static const struct acpi_device_id i2c_multi_instantiate_ids[] = {
                 {"BSG1160", },
                 {}
         };

For v4.

Regards,

Hans