Re: [PATCH] iio: adc: qcom-spmi-adc5-gen3: Reuse IIO device ID for ADC_TM auxiliary device

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 28 Oct 2026 15:09:47 +0100
Loic Poulain <loic.poulain@oss.qualcomm.com> wrote:

Hi Loic,

> A recent fix in ADC5 Gen3 driver allocates a dedicated auxiliary-device
> ID through an IDA to ensure that ADC_TM auxiliary devices receive unique
> names on the auxiliary bus.
When talking about another patch I'd refer to it by name and ideally
also add a Link tag to the lore.kernel.org for it to the tags block.
I think you mean:

iio: adc: qcom-spmi-adc5-gen3: Allocate unique ADC_TM aux device IDs
Link: https://lore.kernel.org/all/20261008031154.3440632-1-shengchao.guo@oss.qualcomm.com/

> 
> However, each ADC instance is already assigned a unique IIO device ID.
> Reuse that existing identifier when registering the ADC_TM auxiliary
> device instead of maintaining a separate IDA solely for auxiliary device
> naming.
> 
> This removes the custom ID allocation and release handling while
> preserving unique auxiliary device names across multiple ADC instances.

> 
> Signed-off-by: Loic Poulain <loic.poulain@oss.qualcomm.com>


The fix hasn't gone upstream yet (assuming it is the patch I think
it is!).  Would it be better to just squash this onto that patch
and avoid having to care about a version of the intermediate code?

+CC Shawn. 

Thanks,

Jonathan

> ---
>  drivers/iio/adc/qcom-spmi-adc5-gen3.c | 24 +++++-------------------
>  1 file changed, 5 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/iio/adc/qcom-spmi-adc5-gen3.c b/drivers/iio/adc/qcom-spmi-adc5-gen3.c
> index f0b2544c16322374644ac3a2eda63322f318e25f..a23eb5c9096d765af7d76ad66b50ed895782b256 100644
> --- a/drivers/iio/adc/qcom-spmi-adc5-gen3.c
> +++ b/drivers/iio/adc/qcom-spmi-adc5-gen3.c
> @@ -15,7 +15,6 @@
>  #include <linux/dev_printk.h>
>  #include <linux/err.h>
>  #include <linux/export.h>
> -#include <linux/idr.h>
>  #include <linux/iio/adc/qcom-adc5-gen3-common.h>
>  #include <linux/iio/iio.h>
>  #include <linux/interrupt.h>
> @@ -609,16 +608,9 @@ static void adc5_gen3_delete_aux(void *data)
>  	auxiliary_device_delete(data);
>  }
>  
> -static DEFINE_IDA(adc5_gen3_aux_ida);
> +static void adc5_gen3_aux_device_release(struct device *dev) {}
>  
> -static void adc5_gen3_aux_device_release(struct device *dev)
> -{
> -	struct auxiliary_device *adev = to_auxiliary_dev(dev);
> -
> -	ida_free(&adc5_gen3_aux_ida, adev->id);n
> -}
> -
> -static int adc5_gen3_add_aux_tm_device(struct adc5_chip *adc)
> +static int adc5_gen3_add_aux_tm_device(struct adc5_chip *adc, int id)
>  {
>  	struct tm5_aux_dev_wrapper *aux_device;
>  	int i, ret, i_tm = 0;
> @@ -628,6 +620,7 @@ static int adc5_gen3_add_aux_tm_device(struct adc5_chip *adc)
>  		return -ENOMEM;
>  
>  	aux_device->aux_dev.name = "adc5_tm_gen3";
> +	aux_device->aux_dev.id = id;
>  	aux_device->aux_dev.dev.parent = adc->dev;
>  	aux_device->aux_dev.dev.release = adc5_gen3_aux_device_release;
>  
> @@ -650,16 +643,9 @@ static int adc5_gen3_add_aux_tm_device(struct adc5_chip *adc)
>  
>  	aux_device->n_tm_channels = adc->n_tm_channels;
>  
> -	ret = ida_alloc(&adc5_gen3_aux_ida, GFP_KERNEL);
> -	if (ret < 0)
> -		return ret;
> -	aux_device->aux_dev.id = ret;
> -
>  	ret = auxiliary_device_init(&aux_device->aux_dev);
> -	if (ret) {
> -		ida_free(&adc5_gen3_aux_ida, aux_device->aux_dev.id);
> +	if (ret)
>  		return ret;
> -	}
>  
>  	ret = devm_add_action_or_reset(adc->dev, adc5_gen3_uninit_aux,
>  				       &aux_device->aux_dev);
> @@ -814,7 +800,7 @@ static int adc5_gen3_probe(struct platform_device *pdev)
>  		return ret;
>  
>  	if (adc->n_tm_channels > 0) {
> -		ret = adc5_gen3_add_aux_tm_device(adc);
> +		ret = adc5_gen3_add_aux_tm_device(adc, iio_device_id(indio_dev));
>  		if (ret)
>  			dev_err_probe(dev, ret,
>  				      "Failed to add auxiliary TM device\n");
> 
> ---
> base-commit: f1ac44c32cba88ad65dcecd4a279661d14e93651
> change-id: 20261028-fix-adc5-tm-c96b13a4f442
> 
> Best regards,