Re: [PATCH] iio: mma8452: Fix 'mma8452_dt_ids' defined but not used compiler warning

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Mon, 14 Feb 2022 10:18:50 +0100
Hans de Goede <hdegoede@redhat.com> wrote:

> Commit 90adc57bd55a ("iio: mma8452: Fix probe failing when an
> i2c_device_id is used") introduces a new: "'mma8452_dt_ids' defined
> but not used" compiler warning.
> 
> This is caused by the switch from of_match_device() (which takes a
> pointer to this) to device_get_match_data(), combined with the use of
> of_match_ptr() when setting of_match_table.
> 
> We actually want mma8452_dt_ids to get optmized away when CONFIG_OF is
> not set, so mark it as __maybe_unused to silence the warning.
> 
> Fixes: 90adc57bd55a ("iio: mma8452: Fix probe failing when an i2c_device_id is used")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

For this I'd rather drop the of_match_ptr() protection.

We will need to do that anyway shortly as part of converting this
to fully device properties and allowing ACPI PRP0001 which uses
the of_match_table from ACPI.

We can now easily make that transition as (via Andy)
https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git/commit/?h=i2c/alert-for-acpi&id=ca0acb511c21738b32386ce0f85c284b351d919e

Anyhow, I can just fix it up on the original patch once I'm on the
right computer.  I might also post patches to get rid
of the of dependency completely if no one else gets there
before me.

Thanks,

Jonathan


> ---
> Note the 90adc57bd55a hash is from the jic23/iio.git testing branch, not
> sure of it is stable. It is probably best to just squash this into the
> original commit.
> ---
>  drivers/iio/accel/mma8452.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index 590d9431e1bd..1324bd515377 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -1529,7 +1529,7 @@ static int mma8452_reset(struct i2c_client *client)
>  	return -ETIMEDOUT;
>  }
>  
> -static const struct of_device_id mma8452_dt_ids[] = {
> +static const struct of_device_id __maybe_unused mma8452_dt_ids[] = {
>  	{ .compatible = "fsl,mma8451", .data = &mma_chip_info_table[mma8451] },
>  	{ .compatible = "fsl,mma8452", .data = &mma_chip_info_table[mma8452] },
>  	{ .compatible = "fsl,mma8453", .data = &mma_chip_info_table[mma8453] },