Re: [PATCH v2 09/12] media: ov2740: Return -EPROBE_DEFER if no endpoint is found

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

Thank you for the patch.

On Mon, Sep 18, 2023 at 03:51:35PM +0300, Sakari Ailus wrote:
> With ipu bridge, endpoints may only be created when ipu bridge has
> initialised. This may happen after the sensor driver has first probed.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/i2c/ov2740.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c
> index 2c00e653ec47..ccbb15e730ae 100644
> --- a/drivers/media/i2c/ov2740.c
> +++ b/drivers/media/i2c/ov2740.c
> @@ -976,7 +976,7 @@ static int ov2740_check_hwcfg(struct device *dev)
>  
>  	ep = fwnode_graph_get_next_endpoint(fwnode, NULL);
>  	if (!ep)
> -		return -ENXIO;
> +		return -EPROBE_DEFER;

This is fine as a quick fix, so

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

but I'm thinking that we need better in the long run, for multiple
reasons:

- All sensor drivers that support ACPI should do the same, as they
  shouldn't be aware of platform-specific integration details. This
  could be done by mass-patching them, with a documentation update to
  clearly indicate what error code is appropriate. Another option could
  be to return an error pointer from fwnode_graph_get_next_endpoint(),
  with the appropriate error being set depending on the platform. Other
  solutions may be possible too.

- On OF systems, a DT error will result in probe deferral, which is
  harder to debug than probe failures. It would be nice to avoid that.

>  
>  	ret = v4l2_fwnode_endpoint_alloc_parse(ep, &bus_cfg);
>  	fwnode_handle_put(ep);

-- 
Regards,

Laurent Pinchart