Re: [PATCH v1 1/2] driver core: fw_devlink: Allow firmware to mark devices as best effort

[Sascha Hauer <sha@xxxxxxxxxxxxxx>]

On Wed, Jun 22, 2022 at 02:59:10PM -0700, Saravana Kannan wrote:
> When firmware sets the FWNODE_FLAG_BEST_EFFORT flag for a fwnode,
> fw_devlink will do a best effort ordering for that device where it'll
> only enforce the probe/suspend/resume ordering of that device with
> suppliers that have drivers. The driver of that device can then decide
> if it wants to defer probe or probe without the suppliers.
> 
> This will be useful for avoid probe delays of the console device that
> were caused by commit 71066545b48e ("driver core: Set
> fw_devlink.strict=1 by default").
> 
> Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
> Reported-by: Sascha Hauer <sha@xxxxxxxxxxxxxx>
> Reported-by: Peng Fan <peng.fan@xxxxxxx>
> Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> ---
>  drivers/base/core.c    | 3 ++-
>  include/linux/fwnode.h | 4 ++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 839f64485a55..61edd18b7bf3 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -968,7 +968,8 @@ static void device_links_missing_supplier(struct device *dev)
>  
>  static bool dev_is_best_effort(struct device *dev)
>  {
> -	return fw_devlink_best_effort && dev->can_match;
> +	return (fw_devlink_best_effort && dev->can_match) ||
> +		dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT;

Check for dev->fwnode first. I am running in a NULL pointer exception
here for a device that doesn't have a fwnode.

Sascha


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