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Subject: Re: [PATCH v2] Input: atmel_mxt_ts - Add maxtouch to I2C table for
 module autoload
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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 <20151120191558.GD26895@dtor-ws> <564F7550.1080300@osg.samsung.com>
From: Javier Martinez Canillas <javier@osg.samsung.com>
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Cc: linux-kernel@vger.kernel.org, Nick Dyer <nick.dyer@itdev.co.uk>,
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Date: Fri, 20 Nov 2015 16:46:17 -0300
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On 11/20/2015 04:32 PM, Javier Martinez Canillas wrote:

[snip]

> 
> But is not complete because the .driver_data in i2c_device_id is an
> kernel_ulong_t while the .data in of_device_id is a const void * so
> some casting will be needed to add an OF table in some drivers that

Some casting in the tables *and* some logic to get the .data from the
OF table entries, so something like the following will be needed:

static int foo_i2c_probe(struct i2c_client *i2c,
                         const struct i2c_device_id *id)
{
        struct of_device_id *match;
        kernel_ulong_t data;

        if (i2c->dev.of_node) {
               match = of_match_node(of_match, i2c->dev.of_node);
	       if (!match)
                        return -EINVAL;

               data = (kernel_ulong_t)match->data;
        } else {
               data = id->driver_data;
	}
	...
}

while currently I2C drivers just rely on the model part of the compatible
string to match with the entry in the I2C device ID table and the core
always passing the correct .driver_data to the probe function.

So as you can see, converting all the drivers to not rely on the I2C table
requires some refactoring before proper OF modalias reporting can be used.

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America