netdev - Re: [PATCH net-next 4/5] tsnep: Add TSN endpoint Ethernet MAC driver

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Message-ID: <YP8f8lXieL+Ld1eW@lunn.ch>
Date:   Mon, 26 Jul 2021 22:49:54 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Gerhard Engleder <gerhard@...leder-embedded.com>
Cc:     davem@...emloft.net, kuba@...nel.org, robh+dt@...nel.org,
        michal.simek@...inx.com, netdev@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH net-next 4/5] tsnep: Add TSN endpoint Ethernet MAC driver

Hi Gerhard

> +int tsnep_read_md(struct tsnep_adapter *adapter, int phy, int reg, u16 *data)
> +{
> +	u32 md;
> +	int retval = 0;
> +
> +	if (mutex_lock_interruptible(&adapter->md_lock) != 0)
> +		return -ERESTARTSYS;

This probably means you have something wrong with your architecture.
The core mdio layer will serialise access to the mdio bus. So you
should not need such locks.

> +int tsnep_enable_loopback(struct tsnep_adapter *adapter, int speed)
> +{
> +	int phy_address = adapter->phydev->mdio.addr;
> +	u16 val;
> +	int retval;
> +
> +	adapter->loopback = true;
> +	adapter->loopback_speed = speed;
> +
> +	retval = tsnep_read_md(adapter, phy_address, MII_BMCR, &val);

And this might be why you have these locks?

A MAC driver should never directly touch the PHY hardware. Use the
phy_loopback(phydev) call.

	Andrew