linux-kernel - Re: [PATCH 3/8] nvmem: Add nvmem_cell_get_optional and devm_nvmem_cell_get

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Date:   Tue, 15 Jan 2019 12:40:53 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Alban Bedel <albeu@...e.fr>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/8] nvmem: Add nvmem_cell_get_optional and
 devm_nvmem_cell_get_optional



On 06/01/2019 19:28, Alban Bedel wrote:
> Add helper functions to make the driver code simpler when a cell is
> optional. Using these functions just return NULL when the cell doesn't
> exists or if nvmem is disabled.
> 
> Signed-off-by: Alban Bedel<albeu@...e.fr>
> ---
>   drivers/nvmem/core.c           | 48 ++++++++++++++++++++++++++++++++++
>   include/linux/nvmem-consumer.h | 16 ++++++++++++
>   2 files changed, 64 insertions(+)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index f8c43da6f2ca..8e1b52559467 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -1083,6 +1083,30 @@ struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
>   }
>   EXPORT_SYMBOL_GPL(nvmem_cell_get);
>   
> +/**
> + * nvmem_cell_get_optional() - Get an optional nvmem cell of device from
> + * a given id.
> + *
> + * @dev: Device that requests the nvmem cell.
> + * @cell_id: nvmem cell name to get.
> + *
> + * Return: Will be NULL if no cell with the given name is defined,
> + * an ERR_PTR() on error or a valid pointer to a struct nvmem_cell.
> + * The nvmem_cell will be freed by the nvmem_cell_put().
> + */
> +struct nvmem_cell *nvmem_cell_get_optional(struct device *dev,
> +					   const char *cell_id)
> +{
> +	struct nvmem_cell *cell;
> +
> +	cell = nvmem_cell_get(dev, cell_id);
> +	if (IS_ERR(cell) && PTR_ERR(cell) == -ENOENT)
> +		return NULL;

What is the real use-case here, it does not make sense to me to add this 
additional call just to return NULL when cell is not found!


--srini
> +
> +	return cell;
> +}