linux-kernel - Re: [PATCH net-next 25/30] net: dsa: mt7530: properly set MT7531_CPU

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Message-ID: <20230526155124.sps74wayui6bydao@skbuf>
Date:   Fri, 26 May 2023 18:51:24 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     arinc9.unal@...il.com
Cc:     Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Daniel Golle <daniel@...rotopia.org>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...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>,
        Bartel Eerdekens <bartel.eerdekens@...stell8.be>,
        erkin.bozoglu@...ont.com, mithat.guner@...ont.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net-next 25/30] net: dsa: mt7530: properly set
 MT7531_CPU_PMAP

On Mon, May 22, 2023 at 03:15:27PM +0300, arinc9.unal@...il.com wrote:
> From: Arınç ÜNAL <arinc.unal@...nc9.com>
> 
> Every bit of the CPU port bitmap for MT7531 and the switch on the MT7988
> SoC represents a CPU port to trap frames to. Currently only the bit that
> corresponds to the first found CPU port is set on the bitmap. Introduce the
> MT7531_CPU_PMAP macro to individually set the bits of the CPU port bitmap.
> Set the CPU port bitmap for MT7531 and the switch on the MT7988 SoC on
> mt753x_cpu_port_enable() which runs on a loop for each CPU port. Add
> comments to explain this.
> 
> According to the document MT7531 Reference Manual for Development Board
> v1.0, the MT7531_CPU_PMAP bits are unset after reset so no need to clear it
> beforehand. Since there's currently no public document for the switch on
> the MT7988 SoC, I assume this is also the case for this switch.
> 
> Tested-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
> ---

Is this supposed to be a bug fix? (incompatibility with past or future
device trees also counts as bugs) If so, it needs a Fixes: tag and to be
targeted towards the "net" tree. Also, the impact of the current behavior
and of the change need to be explained better.

>  drivers/net/dsa/mt7530.c | 15 ++++++++-------
>  drivers/net/dsa/mt7530.h |  3 ++-
>  2 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
> index 58d8738d94d3..0b513e3628fe 100644
> --- a/drivers/net/dsa/mt7530.c
> +++ b/drivers/net/dsa/mt7530.c
> @@ -963,6 +963,13 @@ mt753x_cpu_port_enable(struct dsa_switch *ds, int port)
>  		mt7530_rmw(priv, MT753X_MFC, MT7530_CPU_MASK, MT7530_CPU_EN |
>  			   MT7530_CPU_PORT(port));
>  
> +	/* Add the CPU port to the CPU port bitmap for MT7531 and the switch on
> +	 * the MT7988 SoC. Any frames set for trapping to CPU port will be
> +	 * trapped to the CPU port the user port is affine to.
> +	 */
> +	if (priv->id == ID_MT7531 || priv->id == ID_MT7988)
> +		mt7530_set(priv, MT7531_CFC, MT7531_CPU_PMAP(BIT(port)));
> +

Stylistically, the existence of an indirect call to priv->info->cpu_port_config()
per switch family is a bit dissonant with an explicit check for device id later
in the same function.

>  	/* CPU port gets connected to all user ports of
>  	 * the switch.
>  	 */
> @@ -2315,15 +2322,9 @@ static int
>  mt7531_setup_common(struct dsa_switch *ds)
>  {
>  	struct mt7530_priv *priv = ds->priv;
> -	struct dsa_port *cpu_dp;
>  	int ret, i;
>  
> -	/* BPDU to CPU port */
> -	dsa_switch_for_each_cpu_port(cpu_dp, ds) {
> -		mt7530_rmw(priv, MT7531_CFC, MT7531_CPU_PMAP_MASK,
> -			   BIT(cpu_dp->index));
> -		break;
> -	}
> +	/* Trap BPDUs to the CPU port(s) */
>  	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
>  		   MT753X_BPDU_CPU_ONLY);
>  
> diff --git a/drivers/net/dsa/mt7530.h b/drivers/net/dsa/mt7530.h
> index 5ebb942b07ef..fd2a2f726b8a 100644
> --- a/drivers/net/dsa/mt7530.h
> +++ b/drivers/net/dsa/mt7530.h
> @@ -53,7 +53,8 @@ enum mt753x_id {
>  #define  MT7531_MIRROR_MASK		(0x7 << 16)
>  #define  MT7531_MIRROR_PORT_GET(x)	(((x) >> 16) & 0x7)
>  #define  MT7531_MIRROR_PORT_SET(x)	(((x) & 0x7) << 16)
> -#define  MT7531_CPU_PMAP_MASK		GENMASK(7, 0)
> +#define  MT7531_CPU_PMAP(x)		((x) & 0xff)

You can leave this as ((x) & GENMASK(7, 0))

> +#define  MT7531_CPU_PMAP_MASK		MT7531_CPU_PMAP(~0)

There's no other user of MT7531_CPU_PMAP_MASK, you can remove this.

>  
>  #define MT753X_MIRROR_REG(id)		((((id) == ID_MT7531) || ((id) == ID_MT7988)) ?	\
>  					 MT7531_CFC : MT753X_MFC)
> -- 
> 2.39.2
>