Re: [PATCH] firmware: arm_ffa: Treat missing FF-A feature on a platform as a probe miss

[Nathan Chancellor <nathan@kernel.org>]

On Tue, May 26, 2026 at 11:36:49AM +0100, Sudeep Holla wrote:
> When FF-A initialisation is driven from a platform device probe, systems
> that do not implement FF-A can return -EOPNOTSUPP from the early transport
> or version discovery paths. Driver core treats that as a matched probe
> failure and prints:
> 
>   |  arm-ffa arm-ffa: probe with driver arm-ffa failed with error -95
> 
> That is noisy for a firmware interface that can be absent on otherwise
> valid systems. Driver core already treats -ENODEV and -ENXIO as quiet
> rejected matches, so translate only the early unsupported discovery cases
> to -ENODEV. Keep later setup failures unchanged so real FF-A
> initialisation problems are still reported as probe failures.
> 
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Closes: https://lore.kernel.org/all/20260523001148.GA1319283@ax162
> Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>

Appears to work for me.

Tested-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/firmware/arm_ffa/driver.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
> index 54984e1b9741..0f468362c288 100644
> --- a/drivers/firmware/arm_ffa/driver.c
> +++ b/drivers/firmware/arm_ffa/driver.c
> @@ -2109,7 +2109,7 @@ static int ffa_probe(struct platform_device *pdev)
>  
>  	ret = ffa_transport_init(&invoke_ffa_fn);
>  	if (ret)
> -		return ret;
> +		return ret == -EOPNOTSUPP ? -ENODEV : ret;
>  
>  	drv_info = kzalloc_obj(*drv_info);
>  	if (!drv_info)
> @@ -2117,8 +2117,11 @@ static int ffa_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, drv_info);
>  
>  	ret = ffa_version_check(&drv_info->version);
> -	if (ret)
> +	if (ret) {
> +		if (ret == -EOPNOTSUPP)
> +			ret = -ENODEV;
>  		goto free_drv_info;
> +	}
>  
>  	if (ffa_id_get(&drv_info->vm_id)) {
>  		pr_err("failed to obtain VM id for self\n");
> -- 
> 2.43.0
> 

-- 
Cheers,
Nathan