Re: [PATCHv6 net-next 6/7] net: ibm: emac: generate random MAC if not found

Simon Horman
2024-10-12T13:16:56Z

On Fri, Oct 11, 2024 at 12:56:21PM -0700, Rosen Penev wrote:
> On this Cisco MX60W, u-boot sets the local-mac-address property.
> Unfortunately by default, the MAC is wrong and is actually located on a
> UBI partition. Which means nvmem needs to be used to grab it.
>
> In the case where that fails, EMAC fails to initialize instead of
> generating a random MAC as many other drivers do.
>
> Match behavior with other drivers to have a working ethernet interface.
>
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
> drivers/net/ethernet/ibm/emac/core.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c
> index b9ccaae61c48..faa483790b29 100644
> --- a/drivers/net/ethernet/ibm/emac/core.c
> +++ b/drivers/net/ethernet/ibm/emac/core.c
> @@ -2937,9 +2937,12 @@ static int emac_init_config(struct emac_instance *dev)
>
> /* Read MAC-address */
> err = of_get_ethdev_address(np, dev->ndev);
> - if (err)
> - return dev_err_probe(&dev->ofdev->dev, err,
> - "Can't get valid [local-]mac-address from OF !\n");
> + if (err == -EPROBE_DEFER)
> + return err;
> + if (err) {
> + dev_warn(&dev->ofdev->dev, "Can't get valid mac-address. Generating random.");
> + eth_hw_addr_random(dev->ndev);
> + }

The above seems to take the random path for all errors other than
-EPROBE_DEFER. That seems too broad to me, and perhaps it would
be better to be more specific. Assuming the case that needs
to be covered is -EINVAL (a guess on my part), perhaps something like this
would work? (Completely untested!)

err = of_get_ethdev_address(np, dev->ndev);
if (err == -EINVAL) {
/* An explanation should go here, mentioning Cisco MX60W
* Maybe the logic should even be specific to that hw?
*/
dev_warn(&dev->ofdev->dev, "Can't get valid mac-address. Generating random.");
eth_hw_addr_random(dev->ndev);
} else if (err) {
return dev_err_probe(&dev->ofdev->dev, err,
"Can't get valid [local-]mac-address from OF !\n");
}

Also, should this be a bug fix with a Fixes tag for net?

>
> /* IAHT and GAHT filter parameterization */
> if (emac_has_feature(dev, EMAC_FTR_EMAC4SYNC)) {
> --
> 2.47.0
>