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: <7982894a-029c-585a-9ab5-3a6295c6abaa@arinc9.com>
Date:   Fri, 21 Apr 2023 21:47:16 +0300
From:   Arınç ÜNAL <arinc.unal@...nc9.com>
To:     Daniel Golle <daniel@...rotopia.org>
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>,
        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 21.04.2023 21:42, Daniel Golle wrote:
> 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);

MT7531 has got a different bit on the register for this, 
MT7531_FORCE_LNK. Are you sure PMCR_FORCE_LNK would work for MT7531 too?

Arınç