On Thu, 29 Oct 2020 02:12:21 +0800 DENG Qingfang wrote:
> MT7530/7531 has a global RX packet length register, which can be used
> to set MTU.
>
> Signed-off-by: DENG Qingfang <dqf...@gmail.com>
Please wrap your code at 80 chars.
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index de7692b763d8..7764c66a47c9 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -1021,6 +1021,40 @@ mt7530_port_disable(struct dsa_switch *ds, int port)
> mutex_unlock(&priv->reg_mutex);
> }
>
> +static int
> +mt7530_port_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
> +{
> + struct mt7530_priv *priv = ds->priv;
> + int length;
> +
> + /* When a new MTU is set, DSA always set the CPU port's MTU to the
> largest MTU
> + * of the slave ports. Because the switch only has a global RX length
> register,
> + * only allowing CPU port here is enough.
> + */
> + if (!dsa_is_cpu_port(ds, port))
> + return 0;
> +
> + /* RX length also includes Ethernet header, MTK tag, and FCS length */
> + length = new_mtu + ETH_HLEN + MTK_HDR_LEN + ETH_FCS_LEN;
> + if (length <= 1522)
> + mt7530_rmw(priv, MT7530_GMACCR, MAX_RX_PKT_LEN_MASK,
> MAX_RX_PKT_LEN_1522);
> + else if (length <= 1536)
> + mt7530_rmw(priv, MT7530_GMACCR, MAX_RX_PKT_LEN_MASK,
> MAX_RX_PKT_LEN_1536);
> + else if (length <= 1552)
> + mt7530_rmw(priv, MT7530_GMACCR, MAX_RX_PKT_LEN_MASK,
> MAX_RX_PKT_LEN_1552);
> + else
> + mt7530_rmw(priv, MT7530_GMACCR, MAX_RX_JUMBO_MASK |
> MAX_RX_PKT_LEN_MASK,
> + MAX_RX_JUMBO(DIV_ROUND_UP(length, 1024)) |
> MAX_RX_PKT_LEN_JUMBO);
this line should start under priv, so it aligns to the opening
parenthesis.
Besides, don't you need to reset the JUMBO bit when going from jumbo to
non-jumbo? The mask should always include jumbo.
I assume you're duplicating the mt7530_rmw() for the benefit of the
constant validation, but it seems to be counterproductive here.
> + return 0;
> +}
