Messages in this thread | | | Date | Wed, 28 Apr 2021 10:51:15 +0200 | From | Oleksij Rempel <> | Subject | Re: [PATCH net-next v3 0/6] provide generic net selftest support |
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On Wed, Apr 28, 2021 at 08:06:05AM +0000, Joakim Zhang wrote: > > Hi Florian, > > > -----Original Message----- > > From: Florian Fainelli <f.fainelli@gmail.com> > > Sent: 2021年4月28日 0:41 > > To: Joakim Zhang <qiangqing.zhang@nxp.com>; Oleksij Rempel > > <o.rempel@pengutronix.de> > > Cc: Shawn Guo <shawnguo@kernel.org>; Sascha Hauer > > <s.hauer@pengutronix.de>; Andrew Lunn <andrew@lunn.ch>; Heiner Kallweit > > <hkallweit1@gmail.com>; Fugang Duan <fugang.duan@nxp.com>; > > kernel@pengutronix.de; netdev@vger.kernel.org; > > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; > > dl-linux-imx <linux-imx@nxp.com>; Fabio Estevam <festevam@gmail.com>; > > David Jander <david@protonic.nl>; Russell King <linux@armlinux.org.uk>; > > Philippe Schenker <philippe.schenker@toradex.com> > > Subject: Re: [PATCH net-next v3 0/6] provide generic net selftest support > > > > > > > > On 4/26/2021 9:48 PM, Joakim Zhang wrote: > > > > > >> -----Original Message----- > > >> From: Oleksij Rempel <o.rempel@pengutronix.de> > > >> Sent: 2021年4月23日 12:37 > > >> To: Joakim Zhang <qiangqing.zhang@nxp.com> > > >> Cc: Shawn Guo <shawnguo@kernel.org>; Sascha Hauer > > >> <s.hauer@pengutronix.de>; Andrew Lunn <andrew@lunn.ch>; Florian > > >> Fainelli <f.fainelli@gmail.com>; Heiner Kallweit > > >> <hkallweit1@gmail.com>; Fugang Duan <fugang.duan@nxp.com>; > > >> kernel@pengutronix.de; netdev@vger.kernel.org; > > >> linux-arm-kernel@lists.infradead.org; > > >> linux-kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com>; Fabio > > >> Estevam <festevam@gmail.com>; David Jander <david@protonic.nl>; > > >> Russell King <linux@armlinux.org.uk>; Philippe Schenker > > >> <philippe.schenker@toradex.com> > > >> Subject: Re: [PATCH net-next v3 0/6] provide generic net selftest > > >> support > > >> > > >> Hi Joakim, > > >> > > >> On Fri, Apr 23, 2021 at 03:18:32AM +0000, Joakim Zhang wrote: > > >>> > > >>> Hi Oleksij, > > >>> > > >>> I look both stmmac selftest code and this patch set. For stmmac, if > > >>> PHY > > >> doesn't support loopback, it will fallthrough to MAC loopback. > > >>> You provide this generic net selftest support based on PHY loopback, > > >>> I have a > > >> question, is it possible to extend it also support MAC loopback later? > > >> > > >> Yes. If you have interest and time to implement it, please do. > > >> It should be some kind of generic callback as phy_loopback() and if > > >> PHY and MAC loopbacks are supported we need to tests both variants. > > > Hi Oleksij, > > > > > > Yes, I can try to implement it when I am free, but I still have some questions: > > > 1. Where we place the generic function? Such as mac_loopback(). > > > 2. MAC is different from PHY, need program different registers to enable > > loopback on different SoCs, that means we need get MAC private data from > > "struct net_device". > > > So we need a callback for MAC drivers, where we extend this callback? Could > > be "struct net_device_ops"? Such as ndo_set_loopback? > > > > Even for PHY devices, if we implemented external PHY loopback in the future, > > the programming would be different from one vendor to another. I am starting > > to wonder if the existing ethtool self-tests are the best API to expose the ability > > for an user to perform PHY and MAC loopback testing. > > > > From an Ethernet MAC and PHY driver perspective, what I would imagine we > > could have for a driver API is: > > > > enum ethtool_loopback_mode { > > ETHTOOL_LOOPBACK_OFF, > > ETHTOOL_LOOPBACK_PHY_INTERNAL, > > ETHTOOL_LOOPBACK_PHY_EXTERNAL, > > ETHTOOL_LOOPBACK_MAC_INTERNAL, > > ETHTOOL_LOOPBACK_MAC_EXTERNAL, > > ETHTOOL_LOOPBACK_FIXTURE, > > __ETHTOOL_LOOPBACK_MAX > > }; > > What's the difference between internal and external loopback for both PHY and MAC? I am not familiar with these concepts. Thanks.
For example KSZ9031 PHY. It supports two loopback modes. See page 23: https://ww1.microchip.com/downloads/en/DeviceDoc/00002096E.pdf
TI DP83TC811R-Q1 PHY supports 4 modes. See page 27: https://www.ti.com/lit/ds/symlink/dp83tc811r-q1.pdf
> Best Regards, > Joakim Zhang > > int (*ndo_set_loopback_mode)(struct net_device *dev, enum > > ethtool_loopback_mode mode); > > > > and within the Ethernet MAC driver you would do something like this: > > > > switch (mode) { > > case ETHTOOL_LOOPBACK_PHY_INTERNAL: > > case ETHTOOL_LOOPBACK_PHY_EXTERNAL: > > case ETHTOOL_LOOPBACK_OFF: > > ret = phy_loopback(ndev->phydev, mode); > > break; > > /* Other case statements implemented in driver */ > > > > we would need to change the signature of phy_loopback() to accept being > > passed ethtool_loopback_mode so we can support different modes. > > > > Whether we want to continue using the self-tests API, or if we implement a > > new ethtool command in order to request a loopback operation is up for > > discussion. > > -- > > Florian
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