Re: [PATCH V2 2/3] soc: ti: knav_dma: Make knav_dma_open_channel return NULL on error

[Jacob Keller <jacob.e.keller@intel.com>]

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On 9/30/2025 5:16 AM, Nishanth Menon wrote:
> Make knav_dma_open_channel consistently return NULL on error instead of
> ERR_PTR. Currently the header include/linux/soc/ti/knav_dma.h returns NUL
> when the driver is disabled, but the driver implementation returns
> ERR_PTR(-EINVAL), creating API inconsistency for users.
> 

I would word this as indicating that we don't even use ERR_PTR here at all!

> Standardize the error handling by making the function return NULL on all
> error conditions.
> 
> Suggested-by: Simon Horman <horms@kernel.org>
> Signed-off-by: Nishanth Menon <nm@ti.com>
> ---
> Changes in V2:
> * renewed version
> 
>  drivers/soc/ti/knav_dma.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/soc/ti/knav_dma.c b/drivers/soc/ti/knav_dma.c
> index a25ebe6cd503..e69f0946de29 100644
> --- a/drivers/soc/ti/knav_dma.c
> +++ b/drivers/soc/ti/knav_dma.c
> @@ -402,7 +402,7 @@ static int of_channel_match_helper(struct device_node *np, const char *name,
>   * @name:	slave channel name
>   * @config:	dma configuration parameters
>   *
> - * Returns pointer to appropriate DMA channel on success or error.
> + * Returns pointer to appropriate DMA channel on success or NULL on error.
>   */
>  void *knav_dma_open_channel(struct device *dev, const char *name,
>  					struct knav_dma_cfg *config)
> @@ -414,13 +414,13 @@ void *knav_dma_open_channel(struct device *dev, const char *name,
>  
>  	if (!kdev) {
>  		pr_err("keystone-navigator-dma driver not registered\n");
> -		return (void *)-EINVAL;
> +		return NULL;

Wow. The driver doesn't even return ERR_PTR, but just directly casts
-EINVAL to a void *... thats quite ugly. Good to remove this.


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