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Date: Mon, 4 May 2020 11:10:44 +0200
From: Michal Kubecek <mkubecek@...e.cz>
To: netdev@...r.kernel.org
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
Andrew Lunn <andrew@...n.ch>,
"David S. Miller" <davem@...emloft.net>,
Florian Fainelli <f.fainelli@...il.com>,
Heiner Kallweit <hkallweit1@...il.com>,
Jakub Kicinski <kuba@...nel.org>,
Jonathan Corbet <corbet@....net>,
David Jander <david@...tonic.nl>, kernel@...gutronix.de,
linux-kernel@...r.kernel.org, Russell King <linux@...linux.org.uk>,
mkl@...gutronix.de, Marek Vasut <marex@...x.de>,
Christian Herber <christian.herber@....com>
Subject: Re: [PATCH v5 1/2] ethtool: provide UAPI for PHY master/slave
configuration.
On Mon, May 04, 2020 at 09:12:13AM +0200, Oleksij Rempel wrote:
> This UAPI is needed for BroadR-Reach 100BASE-T1 devices. Due to lack of
> auto-negotiation support, we needed to be able to configure the
> MASTER-SLAVE role of the port manually or from an application in user
> space.
>
> The same UAPI can be used for 1000BASE-T or MultiGBASE-T devices to
> force MASTER or SLAVE role. See IEEE 802.3-2018:
> 22.2.4.3.7 MASTER-SLAVE control register (Register 9)
> 22.2.4.3.8 MASTER-SLAVE status register (Register 10)
> 40.5.2 MASTER-SLAVE configuration resolution
> 45.2.1.185.1 MASTER-SLAVE config value (1.2100.14)
> 45.2.7.10 MultiGBASE-T AN control 1 register (Register 7.32)
>
> The MASTER-SLAVE role affects the clock configuration:
>
> -------------------------------------------------------------------------------
> When the PHY is configured as MASTER, the PMA Transmit function shall
> source TX_TCLK from a local clock source. When configured as SLAVE, the
> PMA Transmit function shall source TX_TCLK from the clock recovered from
> data stream provided by MASTER.
>
> iMX6Q KSZ9031 XXX
> ------\ /-----------\ /------------\
> | | | | |
> MAC |<----RGMII----->| PHY Slave |<------>| PHY Master |
> |<--- 125 MHz ---+-<------/ | | \ |
> ------/ \-----------/ \------------/
> ^
> \-TX_TCLK
>
> -------------------------------------------------------------------------------
>
> Since some clock or link related issues are only reproducible in a
> specific MASTER-SLAVE-role, MAC and PHY configuration, it is beneficial
> to provide generic (not 100BASE-T1 specific) interface to the user space
> for configuration flexibility and trouble shooting.
>
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index ac2784192472f..42dda9d2082ee 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1768,6 +1768,90 @@ int genphy_setup_forced(struct phy_device *phydev)
> }
> EXPORT_SYMBOL(genphy_setup_forced);
>
> +static int genphy_setup_master_slave(struct phy_device *phydev)
> +{
> + u16 ctl = 0;
> +
> + if (!phydev->is_gigabit_capable)
> + return 0;
Why did you revert to silently ignoring requests in this case? On the
other hand, we might rather want to do a more generic check which would
handle all drivers not supporting the feature, see below.
[...]
> @@ -287,14 +308,37 @@ static bool ethnl_auto_linkmodes(struct ethtool_link_ksettings *ksettings,
> __ETHTOOL_LINK_MODE_MASK_NBITS);
> }
>
> +static int ethnl_validate_master_slave_cfg(u8 cfg)
> +{
> + switch (cfg) {
> + case MASTER_SLAVE_CFG_MASTER_PREFERRED:
> + case MASTER_SLAVE_CFG_SLAVE_PREFERRED:
> + case MASTER_SLAVE_CFG_MASTER_FORCE:
> + case MASTER_SLAVE_CFG_SLAVE_FORCE:
> + return 1;
> + }
> +
> + return 0;
> +}
Nitpick: bool would be more appropriate as return value.
> +
> static int ethnl_update_linkmodes(struct genl_info *info, struct nlattr **tb,
> struct ethtool_link_ksettings *ksettings,
> bool *mod)
> {
> struct ethtool_link_settings *lsettings = &ksettings->base;
> bool req_speed, req_duplex;
> + const struct nlattr *master_slave_cfg;
> int ret;
>
> + master_slave_cfg = tb[ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG];
> + if (master_slave_cfg) {
> + u8 cfg = nla_get_u8(master_slave_cfg);
> + if (!ethnl_validate_master_slave_cfg(cfg)) {
> + GENL_SET_ERR_MSG(info, "LINKMODES_MASTER_SLAVE_CFG contains not valid value");
> + return -EOPNOTSUPP;
> + }
> + }
Please set also the "bad attribute" in extack, it may help
non-interactive clients.
Also, it would be nice to report error if client wants to set master/slave but
driver does not support it. How about this?
if (master_slave_cfg) {
u8 cfg = nla_get_u8(master_slave_cfg);
if (lsettings->master_slave_cfg == MASTER_SLAVE_CFG_UNSUPPORTED) {
NL_SET_ERR_MSG_ATTR(info->extack, master_slave_cfg,
"master/slave configuration not supported by device");
return -EOPNOTSUPP;
}
if (!ethnl_validate_master_slave_cfg(cfg)) {
NL_SET_ERR_MSG_ATTR(info->extack, master_slave_cfg,
"master/slave value is invalid");
return -EOPNOTSUPP;
}
}
Do you plan to allow handling master/slave also via ioctl()? If yes, we should
also add the sanity checks to ioctl code path. If not, we should prevent
passing non-zero values from userspace to driver.
Other than this, the patch looks good to me.
Michal
> *mod = false;
> req_speed = tb[ETHTOOL_A_LINKMODES_SPEED];
> req_duplex = tb[ETHTOOL_A_LINKMODES_DUPLEX];
> @@ -311,6 +355,7 @@ static int ethnl_update_linkmodes(struct genl_info *info, struct nlattr **tb,
> mod);
> ethnl_update_u8(&lsettings->duplex, tb[ETHTOOL_A_LINKMODES_DUPLEX],
> mod);
> + ethnl_update_u8(&lsettings->master_slave_cfg, master_slave_cfg, mod);
>
> if (!tb[ETHTOOL_A_LINKMODES_OURS] && lsettings->autoneg &&
> (req_speed || req_duplex) &&
> --
> 2.26.2
>
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