linux-kernel - Re: [RFC PATCH net-next 20/22] net: dsa: mt7530: force link-down on MACs before reset on MT7530

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Message-ID: <ZELZAd4O9SyHLkwn@makrotopia.org>
Date:   Fri, 21 Apr 2023 19:42:09 +0100
From:   Daniel Golle <daniel@...rotopia.org>
To:     arinc9.unal@...il.com
Cc:     Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Russell King <linux@...linux.org.uk>,
        Arınç ÜNAL <arinc.unal@...nc9.com>,
        Richard van Schagen <richard@...terhints.com>,
        Richard van Schagen <vschagen@...com>,
        Frank Wunderlich <frank-w@...lic-files.de>,
        erkin.bozoglu@...ont.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [RFC PATCH net-next 20/22] net: dsa: mt7530: force link-down on
 MACs before reset on MT7530

On Fri, Apr 21, 2023 at 05:36:46PM +0300, arinc9.unal@...il.com wrote:
> From: Arınç ÜNAL <arinc.unal@...nc9.com>
> 
> Force link-down on all MACs before internal reset. Let's follow suit commit
> 728c2af6ad8c ("net: mt7531: ensure all MACs are powered down before
> reset").
> 
> Tested-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> ---
>  drivers/net/dsa/mt7530.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index ac1e3c58aaac..8ece3d0d820c 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -2203,6 +2203,10 @@ mt7530_setup(struct dsa_switch *ds)
>  		return -EINVAL;
>  	}
>  
> +	/* Force link-down on all MACs before internal reset */
> +	for (i = 0; i < MT7530_NUM_PORTS; i++)
> +		mt7530_write(priv, MT7530_PMCR_P(i), PMCR_FORCE_LNK);
> +

Moving this part to mt753x_setup just before calling priv->info->sw_setup(ds);
is probably better. Though it isn't documented I assume that the requirement
to have the ports in force-link-down may also apply to MT7988, and for sure
it doesn't do any harm.

Hence I suggest to squash this change:
diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index a2cb7e296165e..998c4e8930cd3 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -2203,10 +2203,6 @@ mt7530_setup(struct dsa_switch *ds)
 		return -EINVAL;
 	}
 
-	/* Force link-down on all MACs before internal reset */
-	for (i = 0; i < MT7530_NUM_PORTS; i++)
-		mt7530_write(priv, MT7530_PMCR_P(i), PMCR_FORCE_LNK);
-
 	/* Reset the switch through internal reset */
 	mt7530_write(priv, MT7530_SYS_CTRL,
 		     SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |
@@ -2423,10 +2419,6 @@ mt7531_setup(struct dsa_switch *ds)
 		dev_info(priv->dev, "found MT7531BE\n");
 	}
 
-	/* all MACs must be forced link-down before sw reset */
-	for (i = 0; i < MT7530_NUM_PORTS; i++)
-		mt7530_write(priv, MT7530_PMCR_P(i), MT7531_FORCE_LNK);
-
 	/* Reset the switch through internal reset */
 	mt7530_write(priv, MT7530_SYS_CTRL,
 		     SYS_CTRL_PHY_RST | SYS_CTRL_SW_RST |
@@ -2907,6 +2899,10 @@ mt753x_setup(struct dsa_switch *ds)
 		priv->pcs[i].port = i;
 	}
 
+	/* Force link-down on all MACs before setup */
+	for (i = 0; i < MT7530_NUM_PORTS; i++)
+		mt7530_write(priv, MT7530_PMCR_P(i), PMCR_FORCE_LNK);
+
 	ret = priv->info->sw_setup(ds);
 	if (ret)
 		return ret;