Re: [PATCH v1 net-next] net: dsa: Allow only up to two HSR HW offloaded ports for KSZ9477

[Dan Carpenter <dan.carpenter@linaro.org>]

On Tue, Jun 18, 2024 at 03:04:33PM +0200, Lukasz Majewski wrote:
> The KSZ9477 allows HSR in-HW offloading for any of two selected ports.
> This patch adds check if one tries to use more than two ports with
> HSR offloading enabled.
> 
> Signed-off-by: Lukasz Majewski <lukma@denx.de>

Is this a bug fix?  What is the impact for the user?  Fixes tag?  Add
this information to the commit message when you resend.

> ---
>  drivers/net/dsa/microchip/ksz_common.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> index 2818e24e2a51..0d68f0a5bf19 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -3913,6 +3913,9 @@ static int ksz_hsr_join(struct dsa_switch *ds, int port, struct net_device *hsr,
>  	if (ret)
>  		return ret;
>  
> +	if (dev->chip_id == KSZ9477_CHIP_ID && hweight8(dev->hsr_ports) > 1)
> +		return -EOPNOTSUPP;

Put this condition before the ksz_switch_macaddr_get().  Otherwise we'd
need to do a ksz_switch_macaddr_put().

If dev->chip_id != KSZ9477_CHIP_ID then we would have already returned.
Really, that should be the first check in this function.  The
hsr_get_version() should be moved to right before we use the version.
(But that's a separate issue, not related to this patch so ignore it).

So do something like this but write a better error message.

regards,
dan carpenter

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 2818e24e2a51..181e81af3a78 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -3906,6 +3906,11 @@ static int ksz_hsr_join(struct dsa_switch *ds, int port, struct net_device *hsr,
 		return -EOPNOTSUPP;
 	}
 
+	if (hweight8(dev->hsr_ports) > 1) {
+		NL_SET_ERR_MSG_MOD(extack, "Cannot offload more than two ports (in use=0x%x)", dev->hsr_ports);
+		return -EOPNOTSUPP;
+	}
+
 	/* Self MAC address filtering, to avoid frames traversing
 	 * the HSR ring more than once.
 	 */