[PATCH RFC net-next v2 0/2] net: phy: mxl-gpy: broken interrupt fixes

[PATCH RFC net-next v2 0/2] net: phy: mxl-gpy: broken interrupt fixes

[Michael Walle]

The GPY215 has a broken interrupt pin. This patch series tries to
workaround that and because in general that is not possible, disables the
interrupts by default and falls back to polling mode. There is an opt-in
via the devicetree.

The devicetree binding is missing for now because there is still an
ongoing discussion. I'm sending this, because I want to get some feedback
on the new handling in the phy core. As Andrew pointed out, we cannot
change the irq in the PHY's .probe() because a MAC driver might overwrite
it afterwards, e.g. the stmmac does so. Instead introduce a new flag which
can be set by the PHY driver and which is evaluated just before the PHY is
attached and thus the interrupt is requested.

Btw. I'm not sure dev_flags is the correct place here. I couldn't see
when to use dev_flags and when to use the plain one-bit properties in the
struct phy_device. The latter seems to be used internally, but of course
there is at least one exception, the .mac_managed_pm is set by the MAC
drivers.

v2:
 - new handling of how to disable the interrupts

Michael Walle (2):
  net: phy: allow a phy to opt-out of interrupt handling
  net: phy: mxl-gpy: disable interrupts on GPY215 by default

 drivers/net/phy/mxl-gpy.c    | 5 +++++
 drivers/net/phy/phy_device.c | 7 +++++++
 include/linux/phy.h          | 2 ++
 3 files changed, 14 insertions(+)

-- 
2.30.2

[PATCH RFC net-next v2 1/2] net: phy: allow a phy to opt-out of interrupt handling

[Michael Walle]

Until now, it is not possible for a PHY driver to disable interrupts
during runtime. If a driver offers the .config_intr() as well as the
.handle_interrupt() ops, it is eligible for interrupt handling.
Introduce a new flag for the dev_flags property of struct phy_device, which
can be set by PHY driver to skip interrupt setup and fall back to polling
mode.

At the moment, this is used for the MaxLinear PHY which has broken
interrupt handling and there is a need to disable interrupts in some
cases.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/net/phy/phy_device.c | 7 +++++++
 include/linux/phy.h          | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 716870a4499c..e4562859ac00 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1487,6 +1487,13 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 
 	phydev->interrupts = PHY_INTERRUPT_DISABLED;
 
+	/* PHYs can request to use poll mode even though they have an
+	 * associated interrupt line. This could be the case if they
+	 * detect a broken interrupt handling.
+	 */
+	if (phydev->dev_flags & PHY_F_NO_IRQ)
+		phydev->irq = PHY_POLL;
+
 	/* Port is set to PORT_TP by default and the actual PHY driver will set
 	 * it to different value depending on the PHY configuration. If we have
 	 * the generic PHY driver we can't figure it out, thus set the old
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 71eeb4e3b1fd..f1566c7e47a8 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -82,6 +82,8 @@ extern const int phy_10gbit_features_array[1];
 #define PHY_POLL_CABLE_TEST	0x00000004
 #define MDIO_DEVICE_IS_PHY	0x80000000
 
+#define PHY_F_NO_IRQ		0x80000000
+
 /**
  * enum phy_interface_t - Interface Mode definitions
  *
-- 
2.30.2

[PATCH RFC net-next v2 2/2] net: phy: mxl-gpy: disable interrupts on GPY215 by default

[Michael Walle]

The interrupts on the GPY215B and GPY215C are broken and the only viable
fix is to disable them altogether. There is still the possibilty to
opt-in via the device tree.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/net/phy/mxl-gpy.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/phy/mxl-gpy.c b/drivers/net/phy/mxl-gpy.c
index 147d7a5a9b35..e5972b4ef6e8 100644
--- a/drivers/net/phy/mxl-gpy.c
+++ b/drivers/net/phy/mxl-gpy.c
@@ -12,6 +12,7 @@
 #include <linux/mutex.h>
 #include <linux/phy.h>
 #include <linux/polynomial.h>
+#include <linux/property.h>
 #include <linux/netdevice.h>
 
 /* PHY ID */
@@ -292,6 +293,10 @@ static int gpy_probe(struct phy_device *phydev)
 	phydev->priv = priv;
 	mutex_init(&priv->mbox_lock);
 
+	if (gpy_has_broken_mdint(phydev) &&
+	    !device_property_present(dev, "maxlinear,use-broken-interrupts"))
+		phydev->dev_flags |= PHY_F_NO_IRQ;
+
 	fw_version = phy_read(phydev, PHY_FWV);
 	if (fw_version < 0)
 		return fw_version;
-- 
2.30.2

Re: [PATCH RFC net-next v2 1/2] net: phy: allow a phy to opt-out of interrupt handling

[Florian Fainelli]

On 12/28/2022 8:40 AM, Michael Walle wrote:
> Until now, it is not possible for a PHY driver to disable interrupts
> during runtime. If a driver offers the .config_intr() as well as the
> .handle_interrupt() ops, it is eligible for interrupt handling.
> Introduce a new flag for the dev_flags property of struct phy_device, which
> can be set by PHY driver to skip interrupt setup and fall back to polling
> mode.
> 
> At the moment, this is used for the MaxLinear PHY which has broken
> interrupt handling and there is a need to disable interrupts in some
> cases.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
>   drivers/net/phy/phy_device.c | 7 +++++++
>   include/linux/phy.h          | 2 ++
>   2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 716870a4499c..e4562859ac00 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1487,6 +1487,13 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
>   
>   	phydev->interrupts = PHY_INTERRUPT_DISABLED;
>   
> +	/* PHYs can request to use poll mode even though they have an
> +	 * associated interrupt line. This could be the case if they
> +	 * detect a broken interrupt handling.
> +	 */
> +	if (phydev->dev_flags & PHY_F_NO_IRQ)
> +		phydev->irq = PHY_POLL;

Cannot you achieve the same thing with the PHY driver mangling 
phydev->irq to a negative value, or is that too later already by the 
time your phy driver's probe function is running?

> +
>   	/* Port is set to PORT_TP by default and the actual PHY driver will set
>   	 * it to different value depending on the PHY configuration. If we have
>   	 * the generic PHY driver we can't figure it out, thus set the old
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 71eeb4e3b1fd..f1566c7e47a8 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -82,6 +82,8 @@ extern const int phy_10gbit_features_array[1];
>   #define PHY_POLL_CABLE_TEST	0x00000004
>   #define MDIO_DEVICE_IS_PHY	0x80000000
>   
> +#define PHY_F_NO_IRQ		0x80000000

Kudos for using the appropriate namespace for dev_flags :)
-- 
Florian

Re: [PATCH RFC net-next v2 1/2] net: phy: allow a phy to opt-out of interrupt handling

[Andrew Lunn]

On Wed, Dec 28, 2022 at 08:49:35AM -0800, Florian Fainelli wrote:
> 
> 
> On 12/28/2022 8:40 AM, Michael Walle wrote:
> > Until now, it is not possible for a PHY driver to disable interrupts
> > during runtime. If a driver offers the .config_intr() as well as the
> > .handle_interrupt() ops, it is eligible for interrupt handling.
> > Introduce a new flag for the dev_flags property of struct phy_device, which
> > can be set by PHY driver to skip interrupt setup and fall back to polling
> > mode.
> > 
> > At the moment, this is used for the MaxLinear PHY which has broken
> > interrupt handling and there is a need to disable interrupts in some
> > cases.
> > 
> > Signed-off-by: Michael Walle <michael@walle.cc>
> > ---
> >   drivers/net/phy/phy_device.c | 7 +++++++
> >   include/linux/phy.h          | 2 ++
> >   2 files changed, 9 insertions(+)
> > 
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index 716870a4499c..e4562859ac00 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -1487,6 +1487,13 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
> >   	phydev->interrupts = PHY_INTERRUPT_DISABLED;
> > +	/* PHYs can request to use poll mode even though they have an
> > +	 * associated interrupt line. This could be the case if they
> > +	 * detect a broken interrupt handling.
> > +	 */
> > +	if (phydev->dev_flags & PHY_F_NO_IRQ)
> > +		phydev->irq = PHY_POLL;
> 
> Cannot you achieve the same thing with the PHY driver mangling phydev->irq
> to a negative value, or is that too later already by the time your phy
> driver's probe function is running?

It is actually to early. The interrupt is requested when the MAC
attaches the PHY. There are is at least one MAC driver which assigns
the phydev->irq just before attaching the PHY, a long time after the
PHY has probed.

    Andrew

Re: [PATCH RFC net-next v2 1/2] net: phy: allow a phy to opt-out of interrupt handling

[Russell King (Oracle)]

On Wed, Dec 28, 2022 at 08:49:35AM -0800, Florian Fainelli wrote:
> 
> 
> On 12/28/2022 8:40 AM, Michael Walle wrote:
> > Until now, it is not possible for a PHY driver to disable interrupts
> > during runtime. If a driver offers the .config_intr() as well as the
> > .handle_interrupt() ops, it is eligible for interrupt handling.
> > Introduce a new flag for the dev_flags property of struct phy_device, which
> > can be set by PHY driver to skip interrupt setup and fall back to polling
> > mode.
> > 
> > At the moment, this is used for the MaxLinear PHY which has broken
> > interrupt handling and there is a need to disable interrupts in some
> > cases.
> > 
> > Signed-off-by: Michael Walle <michael@walle.cc>
> > ---
> >   drivers/net/phy/phy_device.c | 7 +++++++
> >   include/linux/phy.h          | 2 ++
> >   2 files changed, 9 insertions(+)
> > 
> > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> > index 716870a4499c..e4562859ac00 100644
> > --- a/drivers/net/phy/phy_device.c
> > +++ b/drivers/net/phy/phy_device.c
> > @@ -1487,6 +1487,13 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
> >   	phydev->interrupts = PHY_INTERRUPT_DISABLED;
> > +	/* PHYs can request to use poll mode even though they have an
> > +	 * associated interrupt line. This could be the case if they
> > +	 * detect a broken interrupt handling.
> > +	 */
> > +	if (phydev->dev_flags & PHY_F_NO_IRQ)
> > +		phydev->irq = PHY_POLL;
> 
> Cannot you achieve the same thing with the PHY driver mangling phydev->irq
> to a negative value, or is that too later already by the time your phy
> driver's probe function is running?
> 
> > +
> >   	/* Port is set to PORT_TP by default and the actual PHY driver will set
> >   	 * it to different value depending on the PHY configuration. If we have
> >   	 * the generic PHY driver we can't figure it out, thus set the old
> > diff --git a/include/linux/phy.h b/include/linux/phy.h
> > index 71eeb4e3b1fd..f1566c7e47a8 100644
> > --- a/include/linux/phy.h
> > +++ b/include/linux/phy.h
> > @@ -82,6 +82,8 @@ extern const int phy_10gbit_features_array[1];
> >   #define PHY_POLL_CABLE_TEST	0x00000004
> >   #define MDIO_DEVICE_IS_PHY	0x80000000
> > +#define PHY_F_NO_IRQ		0x80000000
> 
> Kudos for using the appropriate namespace for dev_flags :)

But eww for placement.

PHY_IS_INTERNAL, PHY_RST_AFTER_CLK_EN, PHY_POLL_CABLE_TEST and
MDIO_DEVICE_IS_PHY are all used for the MDIO driver's flags
member.

This new flag is used for the .dev_flags of phy_device - I feel
that it should be separated from the above definitions. I also
think it could do with a comment, because it's not obvious for
future changes that PHY_F_NO_IRQ is used with .dev_flags.

-- 
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