linux-kernel - Re: [RFC PATCH net-next 09/11] net: dsa: microchip: lan937x: update port membership with dsa port

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Message-ID: <20230203234742.jpjxcmaulmk6vgvg@skbuf>
Date:   Sat, 4 Feb 2023 01:47:42 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Rakesh Sankaranarayanan <rakesh.sankaranarayanan@...rochip.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        andrew@...n.ch, f.fainelli@...il.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        woojung.huh@...rochip.com, UNGLinuxDriver@...rochip.com,
        linux@...linux.org.uk
Subject: Re: [RFC PATCH net-next 09/11] net: dsa: microchip: lan937x: update
 port membership with dsa port

On Thu, Feb 02, 2023 at 06:29:28PM +0530, Rakesh Sankaranarayanan wrote:
> Like cpu port, cascaded port will act as host port in second switch. And
> all ports from both switches should be able to forward packets to cascaded
> ports. Add cascaded port (dev->dsa_port) to each port membership.
> 
> Current design add bit map of user ports as cpu port membership. Include
> cascaded port index as well to this group.
> 
> Signed-off-by: Rakesh Sankaranarayanan <rakesh.sankaranarayanan@...rochip.com>
> ---
>  drivers/net/dsa/microchip/ksz_common.c   |  7 ++++---
>  drivers/net/dsa/microchip/lan937x_main.c |  2 +-
>  include/net/dsa.h                        | 15 +++++++++++++++
>  3 files changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> index 913296c5dd50..b8b7b5b7b52d 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -1748,9 +1748,9 @@ static void ksz_get_strings(struct dsa_switch *ds, int port,
>  
>  static void ksz_update_port_member(struct ksz_device *dev, int port)
>  {
> +	u8 port_member = 0, cpu_port, dsa_port;

Don't need these unimaginative names ("cpu_port", "dsa_port" for what is
actually a port *mask*). You can bitwise-OR the upstream port and the
downstream cascade port directly into "port_member", and the code in
ksz_update_port_member() would tolerate it just fine.

>  	struct ksz_port *p = &dev->ports[port];
>  	struct dsa_switch *ds = dev->ds;
> -	u8 port_member = 0, cpu_port;
>  	const struct dsa_port *dp;
>  	int i, j;
>  
> @@ -1759,6 +1759,7 @@ static void ksz_update_port_member(struct ksz_device *dev, int port)
>  
>  	dp = dsa_to_port(ds, port);
>  	cpu_port = BIT(dsa_upstream_port(ds, port));
> +	dsa_port = BIT(dev->dsa_port);

If dev->dsa_port is 0xff, what is BIT(0xff)?

>  
>  	for (i = 0; i < ds->num_ports; i++) {
>  		const struct dsa_port *other_dp = dsa_to_port(ds, i);
> @@ -1798,10 +1799,10 @@ static void ksz_update_port_member(struct ksz_device *dev, int port)
>  				val |= BIT(j);
>  		}
>  
> -		dev->dev_ops->cfg_port_member(dev, i, val | cpu_port);
> +		dev->dev_ops->cfg_port_member(dev, i, val | cpu_port | dsa_port);
>  	}
>  
> -	dev->dev_ops->cfg_port_member(dev, port, port_member | cpu_port);
> +	dev->dev_ops->cfg_port_member(dev, port, port_member | cpu_port | dsa_port);
>  }
>  
>  static int ksz_sw_mdio_read(struct mii_bus *bus, int addr, int regnum)
> diff --git a/drivers/net/dsa/microchip/lan937x_main.c b/drivers/net/dsa/microchip/lan937x_main.c
> index 5108a3f4bf76..b17bb1ea2a4a 100644
> --- a/drivers/net/dsa/microchip/lan937x_main.c
> +++ b/drivers/net/dsa/microchip/lan937x_main.c
> @@ -198,7 +198,7 @@ void lan937x_port_setup(struct ksz_device *dev, int port, bool cpu_port)
>  				 true);
>  
>  	if (cpu_port)
> -		member = dsa_user_ports(ds);
> +		member = dsa_user_ports(ds) | dsa_dsa_ports(ds);

I'm wondering if a single dsa_switch_for_each_port() list traversal plus
an "if ()" wouldn't be more efficient here.

>  	else
>  		member = BIT(dsa_upstream_port(ds, port));
>  
> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index 55651ad29193..939aa6ff1a38 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -591,6 +591,10 @@ static inline bool dsa_is_user_port(struct dsa_switch *ds, int p)
>  	dsa_switch_for_each_port((_dp), (_ds)) \
>  		if (dsa_port_is_cpu((_dp)))
>  
> +#define dsa_switch_for_each_dsa_port(_dp, _ds) \
> +	dsa_switch_for_each_port((_dp), (_ds)) \
> +		if (dsa_port_is_dsa((_dp)))
> +
>  #define dsa_switch_for_each_cpu_port_continue_reverse(_dp, _ds) \
>  	dsa_switch_for_each_port_continue_reverse((_dp), (_ds)) \
>  		if (dsa_port_is_cpu((_dp)))
> @@ -617,6 +621,17 @@ static inline u32 dsa_cpu_ports(struct dsa_switch *ds)
>  	return mask;
>  }
>  
> +static inline u32 dsa_dsa_ports(struct dsa_switch *ds)
> +{
> +	struct dsa_port *dsa_dp;

can name this just "dp"

> +	u32 mask = 0;
> +
> +	dsa_switch_for_each_dsa_port(dsa_dp, ds)
> +		mask |= BIT(dsa_dp->index);
> +
> +	return mask;
> +}
> +
>  /* Return the local port used to reach an arbitrary switch device */
>  static inline unsigned int dsa_routing_port(struct dsa_switch *ds, int device)
>  {
> -- 
> 2.34.1
>