netdev - Re: [PATCH net v5 4/4] net: dsa: microchip: monitor potential faults in half-duplex mode

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Date: Wed, 5 Jun 2024 03:31:36 +0000
From: <Arun.Ramadoss@...rochip.com>
To: <enguerrand.de-ribaucourt@...oirfairelinux.com>, <netdev@...r.kernel.org>
CC: <linux@...linux.org.uk>, <horms@...nel.org>, <Tristram.Ha@...rochip.com>,
	<Woojung.Huh@...rochip.com>, <hkallweit1@...il.com>,
	<UNGLinuxDriver@...rochip.com>, <andrew@...n.ch>
Subject: Re: [PATCH net v5 4/4] net: dsa: microchip: monitor potential faults
 in half-duplex mode

Hi Enguerrand,


> 
> +int ksz9477_errata_monitor(struct ksz_device *dev, int port,
> +                          u64 tx_late_col)
> +{
> +       u32 pmavbc;
> +       u8 status;
> +       u16 pqm;
> +       int ret;
> +
> +       ret = ksz_pread8(dev, port, REG_PORT_STATUS_0, &status);
> +       if (ret)
> +               return ret;

Blank line after return ret will increase readability.

> +       if (!((status & PORT_INTF_SPEED_MASK) ==
> PORT_INTF_SPEED_MASK) &&

Why this check is needed. Is it to check reserved value 11b.


> +           !(status & PORT_INTF_FULL_DUPLEX)) {
> +               dev_warn_once(dev->dev,
> +                             "Half-duplex detected on port %d,
> transmission halt may occur\n",
> +                             port);
> +               /* Errata DS80000754 recommends monitoring potential
> faults in
> +                * half-duplex mode. The switch might not be able to
> communicate anymore
> +                * in these states.
> +                */
> +               if (tx_late_col != 0) {
> +                       /* Transmission halt with late collisions */
> +                       dev_crit_ratelimited(dev->dev,
> +                                            "TX late collisions
> detected, transmission may be halted on port %d\n",
> +                                            port);
> +               }
> +               ret = ksz_pread16(dev, port, REG_PORT_QM_TX_CNT_0__4,
> &pqm);
> +               if (ret)
> +                       return ret;
> +               ret = ksz_read32(dev, REG_PMAVBC, &pmavbc);
> +               if (ret)
> +                       return ret;
> +               if ((FIELD_GET(PMAVBC_MASK, pmavbc) <= PMAVBC_MIN) ||
> +                   (FIELD_GET(PORT_QM_TX_CNT_M, pqm) >=
> PORT_QM_TX_CNT_MAX)) {
> +                       /* Transmission halt with Half-Duplex and
> VLAN */
> +                       dev_crit_ratelimited(dev->dev,
> +                                            "resources out of
> limits, transmission may be halted\n");
> +               }
> +       }
> +       return ret;
> +}
> +
>  
>