netdev - Re: [PATCH net-next v7 5/6] net: dsa: mv88e6xxx: rmon: Use RMU for reading RMON data

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Message-ID: <YxqbvwlHi4Au0Q5Z@lunn.ch>
Date:   Fri, 9 Sep 2022 03:49:51 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Mattias Forsblad <mattias.forsblad@...il.com>
Cc:     netdev@...r.kernel.org, Vivien Didelot <vivien.didelot@...il.com>,
        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>
Subject: Re: [PATCH net-next v7 5/6] net: dsa: mv88e6xxx: rmon: Use RMU for
 reading RMON data

> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
> index bbdf229c9e71..bd16afa2e1a5 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -1234,16 +1234,30 @@ static int mv88e6xxx_stats_get_stats(struct mv88e6xxx_chip *chip, int port,
>  				     u16 bank1_select, u16 histogram)
>  {
>  	struct mv88e6xxx_hw_stat *stat;
> +	int offset = 0;
> +	u64 high;
>  	int i, j;
>  
>  	for (i = 0, j = 0; i < ARRAY_SIZE(mv88e6xxx_hw_stats); i++) {
>  		stat = &mv88e6xxx_hw_stats[i];
>  		if (stat->type & types) {
> -			mv88e6xxx_reg_lock(chip);
> -			data[j] = _mv88e6xxx_get_ethtool_stat(chip, stat, port,
> -							      bank1_select,
> -							      histogram);
> -			mv88e6xxx_reg_unlock(chip);
> +			if (mv88e6xxx_rmu_available(chip) &&

I was trying to avoid code like this, by the use of the ops.

In terms of code, you are actually reusing very little here. What you
are re-using is the table of statistics. I would add a new function,
not change this function.

> +			    !(stat->type & STATS_TYPE_PORT)) {
> +				if (stat->type & STATS_TYPE_BANK1)
> +					offset = 32;
> +
> +				data[j] = chip->ports[port].rmu_raw_stats[stat->reg + offset];
> +				if (stat->size == 8) {
> +					high = chip->ports[port].rmu_raw_stats[stat->reg + offset
> +							+ 1];
> +					data[j] += (high << 32);
> +				}
> +			} else {
> +				mv88e6xxx_reg_lock(chip);
> +				data[j] = _mv88e6xxx_get_ethtool_stat(chip, stat, port,
> +								      bank1_select, histogram);
> +				mv88e6xxx_reg_unlock(chip);
> +			}
>  
>  			j++;
>  		}

> diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
> index 566d18cf5170..5459037067e6 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.h
> +++ b/drivers/net/dsa/mv88e6xxx/chip.h
> @@ -266,6 +266,7 @@ struct mv88e6xxx_vlan {
>  struct mv88e6xxx_port {
>  	struct mv88e6xxx_chip *chip;
>  	int port;
> +	u64 rmu_raw_stats[64];

That is a lot of space you don't actually need. Once you have a clean
set of functions, you can simply pass the raw data as a parameter.

    Andrew