Re: [PATCH v3 1/2] iio: mma8452: Fix probe failing when an i2c_device_id is used

[Jonathan Cameron <jic23@kernel.org>]

On Tue,  8 Feb 2022 13:43:35 +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.
> 
> Fixes: c3cdd6e48e35 ("iio: mma8452: refactor for seperating chip specific data")
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Applied to the fixes-togreg branch of iio.git and marked for stable.

Thanks,

Jonathan

> ---
> Changes in v3:
> - Store name in struct mma_chip_info and use that to set indio_dev->name
> - Switch to using device_get_match_data() for (potentially) adding ACPI
>   enumeration support in the future
> 
> Changes in v2:
> - Fix the following smatch warning:
>   drivers/iio/accel/mma8452.c:1595 mma8452_probe() error: we previously assumed 'id' could be null (see line 1536)
>   Reported-by: kernel test robot <lkp@intel.com>
>   Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  drivers/iio/accel/mma8452.c | 27 +++++++++++++++++----------
>  1 file changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index 64b82b4503ad..0528717d9f44 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -176,6 +176,7 @@ static const struct mma8452_event_regs trans_ev_regs = {
>   * @enabled_events:		event flags enabled and handled by this driver
>   */
>  struct mma_chip_info {
> +	const char *name;
>  	u8 chip_id;
>  	const struct iio_chan_spec *channels;
>  	int num_channels;
> @@ -1301,6 +1302,7 @@ enum {
>  
>  static const struct mma_chip_info mma_chip_info_table[] = {
>  	[mma8451] = {
> +		.name = "mma8451",
>  		.chip_id = MMA8451_DEVICE_ID,
>  		.channels = mma8451_channels,
>  		.num_channels = ARRAY_SIZE(mma8451_channels),
> @@ -1325,6 +1327,7 @@ static const struct mma_chip_info mma_chip_info_table[] = {
>  					MMA8452_INT_FF_MT,
>  	},
>  	[mma8452] = {
> +		.name = "mma8452",
>  		.chip_id = MMA8452_DEVICE_ID,
>  		.channels = mma8452_channels,
>  		.num_channels = ARRAY_SIZE(mma8452_channels),
> @@ -1341,6 +1344,7 @@ static const struct mma_chip_info mma_chip_info_table[] = {
>  					MMA8452_INT_FF_MT,
>  	},
>  	[mma8453] = {
> +		.name = "mma8453",
>  		.chip_id = MMA8453_DEVICE_ID,
>  		.channels = mma8453_channels,
>  		.num_channels = ARRAY_SIZE(mma8453_channels),
> @@ -1357,6 +1361,7 @@ static const struct mma_chip_info mma_chip_info_table[] = {
>  					MMA8452_INT_FF_MT,
>  	},
>  	[mma8652] = {
> +		.name = "mma8652",
>  		.chip_id = MMA8652_DEVICE_ID,
>  		.channels = mma8652_channels,
>  		.num_channels = ARRAY_SIZE(mma8652_channels),
> @@ -1366,6 +1371,7 @@ static const struct mma_chip_info mma_chip_info_table[] = {
>  		.enabled_events = MMA8452_INT_FF_MT,
>  	},
>  	[mma8653] = {
> +		.name = "mma8653",
>  		.chip_id = MMA8653_DEVICE_ID,
>  		.channels = mma8653_channels,
>  		.num_channels = ARRAY_SIZE(mma8653_channels),
> @@ -1380,6 +1386,7 @@ static const struct mma_chip_info mma_chip_info_table[] = {
>  		.enabled_events = MMA8452_INT_FF_MT,
>  	},
>  	[fxls8471] = {
> +		.name = "fxls8471",
>  		.chip_id = FXLS8471_DEVICE_ID,
>  		.channels = mma8451_channels,
>  		.num_channels = ARRAY_SIZE(mma8451_channels),
> @@ -1522,13 +1529,6 @@ static int mma8452_probe(struct i2c_client *client,
>  	struct mma8452_data *data;
>  	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;
> -	}
>  
>  	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
>  	if (!indio_dev)
> @@ -1537,7 +1537,14 @@ 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;
> +
> +	data->chip_info = device_get_match_data(&client->dev);
> +	if (!data->chip_info && id) {
> +		data->chip_info = &mma_chip_info_table[id->driver_data];
> +	} else {
> +		dev_err(&client->dev, "unknown device model\n");
> +		return -ENODEV;
> +	}
>  
>  	data->vdd_reg = devm_regulator_get(&client->dev, "vdd");
>  	if (IS_ERR(data->vdd_reg))
> @@ -1581,11 +1588,11 @@ 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);
> +		 data->chip_info->name, data->chip_info->chip_id);
>  
>  	i2c_set_clientdata(client, indio_dev);
>  	indio_dev->info = &mma8452_info;
> -	indio_dev->name = id->name;
> +	indio_dev->name = data->chip_info->name;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->channels = data->chip_info->channels;
>  	indio_dev->num_channels = data->chip_info->num_channels;