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Subject[PATCH AUTOSEL for 4.14 001/110] net: phy: fix resume handling
Date
From: Russell King <rmk+kernel@armlinux.org.uk>

[ Upstream commit f5e64032a799d4f54decc7eb6aafcdffb67f9ad9 ]

When a PHY has the BMCR_PDOWN bit set, it may decide to ignore writes
to other registers, or reset the registers to power-on defaults.
Micrel PHYs do this for their interrupt registers.

The current structure of phylib tries to enable interrupts before
resuming (and releasing) the BMCR_PDOWN bit. This fails, causing
Micrel PHYs to stop working after a suspend/resume sequence if they
are using interrupts.

Fix this by ensuring that the PHY driver resume methods do not take
the phydev->lock mutex themselves, but the callers of phy_resume()
take that lock. This then allows us to move the call to phy_resume()
before we enable interrupts in phy_start().

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/net/phy/at803x.c | 4 ----
drivers/net/phy/phy.c | 9 +++------
drivers/net/phy/phy_device.c | 10 ++++++----
3 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
index 5f93e6add563..e911e4990b20 100644
--- a/drivers/net/phy/at803x.c
+++ b/drivers/net/phy/at803x.c
@@ -239,14 +239,10 @@ static int at803x_resume(struct phy_device *phydev)
{
int value;

- mutex_lock(&phydev->lock);
-
value = phy_read(phydev, MII_BMCR);
value &= ~(BMCR_PDOWN | BMCR_ISOLATE);
phy_write(phydev, MII_BMCR, value);

- mutex_unlock(&phydev->lock);
-
return 0;
}

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 2b1e67bc1e73..ed10d1fc8f59 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -828,7 +828,6 @@ EXPORT_SYMBOL(phy_stop);
*/
void phy_start(struct phy_device *phydev)
{
- bool do_resume = false;
int err = 0;

mutex_lock(&phydev->lock);
@@ -841,6 +840,9 @@ void phy_start(struct phy_device *phydev)
phydev->state = PHY_UP;
break;
case PHY_HALTED:
+ /* if phy was suspended, bring the physical link up again */
+ phy_resume(phydev);
+
/* make sure interrupts are re-enabled for the PHY */
if (phydev->irq != PHY_POLL) {
err = phy_enable_interrupts(phydev);
@@ -849,17 +851,12 @@ void phy_start(struct phy_device *phydev)
}

phydev->state = PHY_RESUMING;
- do_resume = true;
break;
default:
break;
}
mutex_unlock(&phydev->lock);

- /* if phy was suspended, bring the physical link up again */
- if (do_resume)
- phy_resume(phydev);
-
phy_trigger_machine(phydev, true);
}
EXPORT_SYMBOL(phy_start);
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 67f25ac29025..b15b31ca2618 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -135,7 +135,9 @@ static int mdio_bus_phy_resume(struct device *dev)
if (!mdio_bus_phy_may_suspend(phydev))
goto no_resume;

+ mutex_lock(&phydev->lock);
ret = phy_resume(phydev);
+ mutex_unlock(&phydev->lock);
if (ret < 0)
return ret;

@@ -1026,7 +1028,9 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
if (err)
goto error;

+ mutex_lock(&phydev->lock);
phy_resume(phydev);
+ mutex_unlock(&phydev->lock);
phy_led_triggers_register(phydev);

return err;
@@ -1157,6 +1161,8 @@ int phy_resume(struct phy_device *phydev)
struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
int ret = 0;

+ WARN_ON(!mutex_is_locked(&phydev->lock));
+
if (phydev->drv && phydrv->resume)
ret = phydrv->resume(phydev);

@@ -1639,13 +1645,9 @@ int genphy_resume(struct phy_device *phydev)
{
int value;

- mutex_lock(&phydev->lock);
-
value = phy_read(phydev, MII_BMCR);
phy_write(phydev, MII_BMCR, value & ~BMCR_PDOWN);

- mutex_unlock(&phydev->lock);
-
return 0;
}
EXPORT_SYMBOL(genphy_resume);
--
2.11.0
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