| Message ID | 20171213173751.12722-1-l.stach@pengutronix.de |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [1/3] net: phy: add support to detect 100BASE-T1 capability | expand |
On Wed, Dec 13, 2017 at 06:37:49PM +0100, Lucas Stach wrote: > 100BASE-T1 is the automotive ethernet standard 802.3bw-2015. Currently > we don't detect any valid modes for PHYs, which only support this > standard. Add support to detect the common 100Mbit full-duplex mode. > > Signed-off-by: Lucas Stach <l.stach@pengutronix.de> > --- > drivers/net/phy/phy_device.c | 2 ++ > include/uapi/linux/mii.h | 1 + > 2 files changed, 3 insertions(+) > > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c > index 67f25ac29025..8ef48b38d97b 100644 > --- a/drivers/net/phy/phy_device.c > +++ b/drivers/net/phy/phy_device.c > @@ -1607,6 +1607,8 @@ int genphy_config_init(struct phy_device *phydev) > if (val < 0) > return val; > > + if (val & ESTATUS_100T1_FULL) > + features |= SUPPORTED_100baseT_Full; Hi Lucas Why did you decide to do this, and not add a SUPPORTED_100baseT1? Could a device support both 100-BASE-T and 100-BASE-T1? If at some point we need to differentiate between them, it is going to be hard. Especially since this is part of the kernel ABI. Andrew
Hi Andrew, Am Mittwoch, den 13.12.2017, 21:11 +0100 schrieb Andrew Lunn: > On Wed, Dec 13, 2017 at 06:37:49PM +0100, Lucas Stach wrote: > > 100BASE-T1 is the automotive ethernet standard 802.3bw-2015. > > Currently > > we don't detect any valid modes for PHYs, which only support this > > standard. Add support to detect the common 100Mbit full-duplex > > mode. > > > > Signed-off-by: Lucas Stach <l.stach@pengutronix.de> > > --- > > drivers/net/phy/phy_device.c | 2 ++ > > include/uapi/linux/mii.h | 1 + > > 2 files changed, 3 insertions(+) > > > > diff --git a/drivers/net/phy/phy_device.c > > b/drivers/net/phy/phy_device.c > > index 67f25ac29025..8ef48b38d97b 100644 > > --- a/drivers/net/phy/phy_device.c > > +++ b/drivers/net/phy/phy_device.c > > @@ -1607,6 +1607,8 @@ int genphy_config_init(struct phy_device > > *phydev) > > if (val < 0) > > return val; > > > > + if (val & ESTATUS_100T1_FULL) > > + features |= SUPPORTED_100baseT_Full; > > Hi Lucas > > Why did you decide to do this, and not add a SUPPORTED_100baseT1? > > Could a device support both 100-BASE-T and 100-BASE-T1? If at some > point we need to differentiate between them, it is going to be > hard. Especially since this is part of the kernel ABI. Networking and especially PHY isn't really my primary area of expertise, so excuse my ignorance. My reasoning was that we don't differentiate between 100BASE-T2 and 100BASE-T4 in the kernel today, so I thought it was fine to handle T1 the same way. There are PHYs that can both do regular 100/1000 MBit Ethernet and 100BASE-T1, but definitely not at the same time or over the same electrical wiring. 100BASE-T1 is really different in that it uses capacitive coupling, instead of magnetic like on regular Ethernet. So it is really a board level decision what gets used and is not something I would expect to change at runtime. I'll leave it to your judgment if this patch seems fine with the above information in mind. Happy to rework if needed. Regards, Lucas
> > Hi Lucas > > > > Why did you decide to do this, and not add a SUPPORTED_100baseT1? > > > > Could a device support both 100-BASE-T and 100-BASE-T1? If at some > > point we need to differentiate between them, it is going to be > > hard. Especially since this is part of the kernel ABI. > > Networking and especially PHY isn't really my primary area of > expertise, so excuse my ignorance. My reasoning was that we don't > differentiate between 100BASE-T2 and 100BASE-T4 in the kernel today, so > I thought it was fine to handle T1 the same way. > > There are PHYs that can both do regular 100/1000 MBit Ethernet and > 100BASE-T1, but definitely not at the same time or over the same > electrical wiring. 100BASE-T1 is really different in that it uses > capacitive coupling, instead of magnetic like on regular Ethernet. So > it is really a board level decision what gets used and is not something > I would expect to change at runtime. Hi Lucus http://www.marvell.com/docs/automotive/assets/marvell-automotive-ethernet-88Q5050-product-brief-2017-07.pdf This is a Marvell 8-port switch. It appears it can switch some of its ports between T1, TX, xMII, GMII and SGMII. So maybe an end device is fixed to 100BASE-T1, but it looks like switches could be more flexible. So i think we should be able to differentiate between T1 and TX. We might also need an PHY_INTERFACE_MODE_100BASE_T1. Florian, what do you think? Andrew
Am Donnerstag, den 14.12.2017, 10:46 +0100 schrieb Andrew Lunn: > > > Hi Lucas > > > > > > Why did you decide to do this, and not add a SUPPORTED_100baseT1? > > > > > > Could a device support both 100-BASE-T and 100-BASE-T1? If at > > > some > > > point we need to differentiate between them, it is going to be > > > hard. Especially since this is part of the kernel ABI. > > > > Networking and especially PHY isn't really my primary area of > > expertise, so excuse my ignorance. My reasoning was that we don't > > differentiate between 100BASE-T2 and 100BASE-T4 in the kernel > > today, so > > I thought it was fine to handle T1 the same way. > > > > There are PHYs that can both do regular 100/1000 MBit Ethernet and > > 100BASE-T1, but definitely not at the same time or over the same > > electrical wiring. 100BASE-T1 is really different in that it uses > > capacitive coupling, instead of magnetic like on regular Ethernet. > > So > > it is really a board level decision what gets used and is not > > something > > I would expect to change at runtime. > > Hi Lucus > > http://www.marvell.com/docs/automotive/assets/marvell-automotive-ethe > rnet-88Q5050-product-brief-2017-07.pdf > > This is a Marvell 8-port switch. It appears it can switch some of its > ports between T1, TX, xMII, GMII and SGMII. > > So maybe an end device is fixed to 100BASE-T1, but it looks like > switches could be more flexible. If you need this for the configuration of the switch in userspace, then yes I agree that we should be able to differentiate between TX and T1. I'll just note that even while you can switch the PHY mode it won't make much sense at runtime, as you won't be able to connect T1 to a switch port that has standard Ethernet magnetics at this PHY port. > So i think we should be able to differentiate between T1 and TX. > We might also need an PHY_INTERFACE_MODE_100BASE_T1. At least the PHYs I've looked at expose regular RGMII or (R)MII to the MAC. Again, if you need this for switch configuration, I'm happy to add it. Regards, Lucas
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 67f25ac29025..8ef48b38d97b 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -1607,6 +1607,8 @@ int genphy_config_init(struct phy_device *phydev) if (val < 0) return val; + if (val & ESTATUS_100T1_FULL) + features |= SUPPORTED_100baseT_Full; if (val & ESTATUS_1000_TFULL) features |= SUPPORTED_1000baseT_Full; if (val & ESTATUS_1000_THALF) diff --git a/include/uapi/linux/mii.h b/include/uapi/linux/mii.h index b5c2fdcf23fd..eb5cc45d23fb 100644 --- a/include/uapi/linux/mii.h +++ b/include/uapi/linux/mii.h @@ -121,6 +121,7 @@ #define EXPANSION_MFAULTS 0x0010 /* Multiple faults detected */ #define EXPANSION_RESV 0xffe0 /* Unused... */ +#define ESTATUS_100T1_FULL 0x0080 /* Can do 100BASE-T1 Full */ #define ESTATUS_1000_TFULL 0x2000 /* Can do 1000BT Full */ #define ESTATUS_1000_THALF 0x1000 /* Can do 1000BT Half */
100BASE-T1 is the automotive ethernet standard 802.3bw-2015. Currently we don't detect any valid modes for PHYs, which only support this standard. Add support to detect the common 100Mbit full-duplex mode. Signed-off-by: Lucas Stach <l.stach@pengutronix.de> --- drivers/net/phy/phy_device.c | 2 ++ include/uapi/linux/mii.h | 1 + 2 files changed, 3 insertions(+)