Subject: Re: [PATCH net-next 1/3] net: dsa: yt921x: Add STP/MST support

From: Simon Horman <[email-masked]>
Date: Fri, 24 Oct 2025 16:52:34 +0100

On Fri, Oct 24, 2025 at 11:32:27AM +0800, David Yang wrote:

...

> +static int
> +yt921x_dsa_vlan_msti_set(struct dsa_switch *ds, struct dsa_bridge bridge,
> +			 const struct switchdev_vlan_msti *msti)
> +{
> +	struct yt921x_priv *priv = to_yt921x_priv(ds);
> +	u64 mask64;
> +	u64 ctrl64;
> +	int res;
> +
> +	if (!msti->vid)
> +		return -EINVAL;
> +	if (msti->msti <= 0 || msti->msti >= YT921X_MSTI_NUM)
> +		return -EINVAL;
> +
> +	mask64 = YT921X_VLAN_CTRL_STP_ID_M;

Hi David,

YT921X_VLAN_CTRL_STP_ID_M is defined as follows in yt931x.h

#define  YT921X_VLAN_CTRL_STP_ID_M              GENMASK(39, 36)

This creates an unsigned long mask. However, on 32bit systems,
unsigned long is only 32 bits wide. So this will result in
a build error on such systems.

In order to avoid this I think the declaration of YT921X_VLAN_CTRL_STP_ID_M
should be updated to use GENMASK_ULL. This is also likely true
for other, as yet unused, #defines in yt931x.h.

> +	ctrl64 = YT921X_VLAN_CTRL_STP_ID(msti->msti);
> +
> +	mutex_lock(&priv->reg_lock);
> +	res = yt921x_reg64_update_bits(priv, YT921X_VLANn_CTRL(msti->vid),
> +				       mask64, ctrl64);
> +	mutex_unlock(&priv->reg_lock);
> +
> +	return res;
> +}

...

-- 
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