[PATCH net-next 0/2] Add Xilinx GMII2RGMII loopback support

[PATCH net-next 0/2] Add Xilinx GMII2RGMII loopback support

[Gerhard Engleder]

The Xilinx GMII2RGMII driver overrides PHY driver functions in order to
configure the device according to the link speed of the PHY attached to it.
This is implemented for a normal link but not for loopback.

Andrew told me to use phy_loopback and this changes make phy_loopback work
in combination with Xilinx GMII2RGMII.

Gerhard Engleder (2):
  net: phy: Support set_loopback override
  net: phy: gmii2rgmii: Support PHY loopback

 drivers/net/phy/phy_device.c        |  9 +++---
 drivers/net/phy/xilinx_gmii2rgmii.c | 46 ++++++++++++++++++++++-------
 2 files changed, 39 insertions(+), 16 deletions(-)

-- 
2.20.1

[PATCH net-next 1/2] net: phy: Support set_loopback override

[Gerhard Engleder]

phy_read_status and various other PHY functions support PHY specific
overriding of driver functions by using a PHY specific pointer to the
PHY driver. Add support of PHY specific override to phy_loopback too.

Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
---
 drivers/net/phy/phy_device.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 107aa6d7bc6b..ba5ad86ec826 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1821,11 +1821,10 @@ EXPORT_SYMBOL(phy_resume);
 
 int phy_loopback(struct phy_device *phydev, bool enable)
 {
-	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
 	int ret = 0;
 
-	if (!phydrv)
-		return -ENODEV;
+	if (!phydev->drv)
+		return -EIO;
 
 	mutex_lock(&phydev->lock);
 
@@ -1839,8 +1838,8 @@ int phy_loopback(struct phy_device *phydev, bool enable)
 		goto out;
 	}
 
-	if (phydrv->set_loopback)
-		ret = phydrv->set_loopback(phydev, enable);
+	if (phydev->drv->set_loopback)
+		ret = phydev->drv->set_loopback(phydev, enable);
 	else
 		ret = genphy_loopback(phydev, enable);
 
-- 
2.20.1

Re: [PATCH net-next 1/2] net: phy: Support set_loopback override

[Andrew Lunn]

On Wed, Aug 18, 2021 at 02:27:35PM +0200, Gerhard Engleder wrote:
> phy_read_status and various other PHY functions support PHY specific
> overriding of driver functions by using a PHY specific pointer to the
> PHY driver. Add support of PHY specific override to phy_loopback too.
> 
> Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
> ---
>  drivers/net/phy/phy_device.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 107aa6d7bc6b..ba5ad86ec826 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1821,11 +1821,10 @@ EXPORT_SYMBOL(phy_resume);
>  
>  int phy_loopback(struct phy_device *phydev, bool enable)
>  {
> -	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
>  	int ret = 0;
>  
> -	if (!phydrv)
> -		return -ENODEV;
> +	if (!phydev->drv)
> +		return -EIO;

Humm, we need to take a closer look at what uses to_phy_driver() and
what uses phydev->drv. Do they need to be different? Can we make it
uniform?

	Andrew

Re: [PATCH net-next 1/2] net: phy: Support set_loopback override

[Gerhard Engleder]

On Wed, Aug 18, 2021 at 5:03 PM Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Wed, Aug 18, 2021 at 02:27:35PM +0200, Gerhard Engleder wrote:
> > phy_read_status and various other PHY functions support PHY specific
> > overriding of driver functions by using a PHY specific pointer to the
> > PHY driver. Add support of PHY specific override to phy_loopback too.
> >
> > Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
> > ---
> >  drivers/net/phy/phy_device.c | 9 ++++-----
> >  1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index 107aa6d7bc6b..ba5ad86ec826 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -1821,11 +1821,10 @@ EXPORT_SYMBOL(phy_resume);
> >
> >  int phy_loopback(struct phy_device *phydev, bool enable)
> >  {
> > -     struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
> >       int ret = 0;
> >
> > -     if (!phydrv)
> > -             return -ENODEV;
> > +     if (!phydev->drv)
> > +             return -EIO;
>
> Humm, we need to take a closer look at what uses to_phy_driver() and
> what uses phydev->drv. Do they need to be different? Can we make it
> uniform?
>
>         Andrew

I saw only 4 references for to_phy_driver():
- phy_loopback() of course
- phy_probe() which uses it to initialize phydev->drv 3 lines later
- mdio_bus_phy_may_suspend() which checks only for valid suspend function
  pointer, but later phy_suspend() uses phydev->drv, so this is at
least inconsistent
- phy_bus_match() which casts from struct device_driver to struct phy_driver

phydev->drv is used much more often and seems to be the right way. I suggest to
also fix mdio_bus_phy_may_suspend(). phy_probe() and phy_bus_match() are
valid uses, because phydev->drv is not available for them.

Do you agree?

Gerhard

Re: [PATCH net-next 1/2] net: phy: Support set_loopback override

[Andrew Lunn]

> I saw only 4 references for to_phy_driver():
> - phy_loopback() of course
> - phy_probe() which uses it to initialize phydev->drv 3 lines later

This is correct. The driver core will set dev.driver to what it thinks
is the correct driver to use, before calling probe.

> - mdio_bus_phy_may_suspend() which checks only for valid suspend function
>   pointer, but later phy_suspend() uses phydev->drv, so this is at
>   least inconsistent

I guess the real question here is, can a device be suspended before it
is probed? It would seem rather odd. So i expect phydev->drv is safe
to use.

> - phy_bus_match() which casts from struct device_driver to struct phy_driver

This is used by the driver core when trying to find a matching
driver. So it is used before phy_probe(). So this is correct.

> 
> phydev->drv is used much more often and seems to be the right way. I suggest to
> also fix mdio_bus_phy_may_suspend(). phy_probe() and phy_bus_match() are
> valid uses, because phydev->drv is not available for them.
> 
> Do you agree?

Agreed. Thanks for spending the time to look at this. I was expecting
there to be more problems than just loopback.

	Andrew

[PATCH net-next 2/2] net: phy: gmii2rgmii: Support PHY loopback

[Gerhard Engleder]

Configure speed if loopback is used. read_status is not called for
loopback.

Signed-off-by: Gerhard Engleder <gerhard@engleder-embedded.com>
---
 drivers/net/phy/xilinx_gmii2rgmii.c | 46 ++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 11 deletions(-)

diff --git a/drivers/net/phy/xilinx_gmii2rgmii.c b/drivers/net/phy/xilinx_gmii2rgmii.c
index 151c2a3f0b3a..8dcb49ed1f3d 100644
--- a/drivers/net/phy/xilinx_gmii2rgmii.c
+++ b/drivers/net/phy/xilinx_gmii2rgmii.c
@@ -27,12 +27,28 @@ struct gmii2rgmii {
 	struct mdio_device *mdio;
 };
 
-static int xgmiitorgmii_read_status(struct phy_device *phydev)
+static void xgmiitorgmii_configure(struct gmii2rgmii *priv, int speed)
 {
-	struct gmii2rgmii *priv = mdiodev_get_drvdata(&phydev->mdio);
 	struct mii_bus *bus = priv->mdio->bus;
 	int addr = priv->mdio->addr;
-	u16 val = 0;
+	u16 val;
+
+	val = mdiobus_read(bus, addr, XILINX_GMII2RGMII_REG);
+	val &= ~XILINX_GMII2RGMII_SPEED_MASK;
+
+	if (speed == SPEED_1000)
+		val |= BMCR_SPEED1000;
+	else if (speed == SPEED_100)
+		val |= BMCR_SPEED100;
+	else
+		val |= BMCR_SPEED10;
+
+	mdiobus_write(bus, addr, XILINX_GMII2RGMII_REG, val);
+}
+
+static int xgmiitorgmii_read_status(struct phy_device *phydev)
+{
+	struct gmii2rgmii *priv = mdiodev_get_drvdata(&phydev->mdio);
 	int err;
 
 	if (priv->phy_drv->read_status)
@@ -42,17 +58,24 @@ static int xgmiitorgmii_read_status(struct phy_device *phydev)
 	if (err < 0)
 		return err;
 
-	val = mdiobus_read(bus, addr, XILINX_GMII2RGMII_REG);
-	val &= ~XILINX_GMII2RGMII_SPEED_MASK;
+	xgmiitorgmii_configure(priv, phydev->speed);
 
-	if (phydev->speed == SPEED_1000)
-		val |= BMCR_SPEED1000;
-	else if (phydev->speed == SPEED_100)
-		val |= BMCR_SPEED100;
+	return 0;
+}
+
+static int xgmiitorgmii_set_loopback(struct phy_device *phydev, bool enable)
+{
+	struct gmii2rgmii *priv = mdiodev_get_drvdata(&phydev->mdio);
+	int err;
+
+	if (priv->phy_drv->set_loopback)
+		err = priv->phy_drv->set_loopback(phydev, enable);
 	else
-		val |= BMCR_SPEED10;
+		err = genphy_loopback(phydev, enable);
+	if (err < 0)
+		return err;
 
-	mdiobus_write(bus, addr, XILINX_GMII2RGMII_REG, val);
+	xgmiitorgmii_configure(priv, phydev->speed);
 
 	return 0;
 }
@@ -90,6 +113,7 @@ static int xgmiitorgmii_probe(struct mdio_device *mdiodev)
 	memcpy(&priv->conv_phy_drv, priv->phy_dev->drv,
 	       sizeof(struct phy_driver));
 	priv->conv_phy_drv.read_status = xgmiitorgmii_read_status;
+	priv->conv_phy_drv.set_loopback = xgmiitorgmii_set_loopback;
 	mdiodev_set_drvdata(&priv->phy_dev->mdio, priv);
 	priv->phy_dev->drv = &priv->conv_phy_drv;
 
-- 
2.20.1