Re: [PATCH] iio: mma8452: Fix probe failing when an i2c_device_id is used

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 1/9/22 16:10, Jonathan Cameron wrote:
> On Thu,  6 Jan 2022 12:14:14 +0100
> Hans de Goede <hdegoede@redhat.com> wrote:
> 
>> The mma8452_driver declares both of_match_table and i2c_driver.id_table
>> match-tables, but its probe() function only checked for of matches.
>>
>> Add support for i2c_device_id matches. This fixes the driver not loading
>> on some x86 tablets (e.g. the Nextbook Ares 8) where the i2c_client is
>> instantiated by platform code using an i2c_device_id.
>>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> Hi Hans,
> 
> At some point we'll want to get rid of the of_ specific stuff in here in
> favour of generic firmware properties and I suspect at that time we'll
> move the device name into the chip_info_table[] entries so that we
> can just use device_get_match_data()
> 
> In the meantime this fix looks good to me.  Is there an appropriate
> Fixes: tag?

I did a quick dive in the git history and the of_match_device() ||
return -ENODEV behavior was introduced in:

c3cdd6e48e35 ("iio: mma8452: refactor for seperating chip specific data")

Regards,

Hans




>> ---
>>  drivers/iio/accel/mma8452.c | 23 +++++++++++++++--------
>>  1 file changed, 15 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
>> index 09c7f10fefb6..c82841c0a7b3 100644
>> --- a/drivers/iio/accel/mma8452.c
>> +++ b/drivers/iio/accel/mma8452.c
>> @@ -1523,12 +1523,7 @@ static int mma8452_probe(struct i2c_client *client,
>>  	struct iio_dev *indio_dev;
>>  	int ret;
>>  	const struct of_device_id *match;
>> -
>> -	match = of_match_device(mma8452_dt_ids, &client->dev);
>> -	if (!match) {
>> -		dev_err(&client->dev, "unknown device model\n");
>> -		return -ENODEV;
>> -	}
>> +	const char *compatible;
>>  
>>  	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
>>  	if (!indio_dev)
>> @@ -1537,7 +1532,19 @@ static int mma8452_probe(struct i2c_client *client,
>>  	data = iio_priv(indio_dev);
>>  	data->client = client;
>>  	mutex_init(&data->lock);
>> -	data->chip_info = match->data;
>> +
>> +	if (id) {
>> +		compatible = id->name;
>> +		data->chip_info = &mma_chip_info_table[id->driver_data];
>> +	} else {
>> +		match = of_match_device(mma8452_dt_ids, &client->dev);
>> +		if (!match) {
>> +			dev_err(&client->dev, "unknown device model\n");
>> +			return -ENODEV;
>> +		}
>> +		compatible = match->compatible;
>> +		data->chip_info = match->data;
>> +	}
>>  
>>  	data->vdd_reg = devm_regulator_get(&client->dev, "vdd");
>>  	if (IS_ERR(data->vdd_reg))
>> @@ -1581,7 +1588,7 @@ static int mma8452_probe(struct i2c_client *client,
>>  	}
>>  
>>  	dev_info(&client->dev, "registering %s accelerometer; ID 0x%x\n",
>> -		 match->compatible, data->chip_info->chip_id);
>> +		 compatible, data->chip_info->chip_id);
>>  
>>  	i2c_set_clientdata(client, indio_dev);
>>  	indio_dev->info = &mma8452_info;
>