[PATCH net-next v2 01/10] net: phy: add error checks in mmd_phy_indirect() and export it

Michael Walle
2023-06-23T10:29:34Z

Add missing error checks in mmd_phy_indirect(). The error checks need to
be disabled to retain the current behavior in phy_read_mmd() and
phy_write_mmd(). Therefore, add a new parameter to enable the error
checks. Add a thin wrapper __phy_mmd_indirect() which is then exported.

Regarding the legacy handling, Russell states:

| The reason for that goes back to commit a59a4d192166 ("phy: add the
| EEE support and the way to access to the MMD registers.")
|
| and to maintain compatibility with that; if we start checking for
| errors now, we might trigger a kernel regression sadly.

Signed-off-by: Michael Walle <mwalle@kernel.org>
---
drivers/net/phy/phy-core.c | 42 ++++++++++++++++++++++++++++++++++--------
include/linux/phy.h | 2 ++
2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
index a64186dc53f8..65ff58b36fc0 100644
--- a/drivers/net/phy/phy-core.c
+++ b/drivers/net/phy/phy-core.c
@@ -524,19 +524,45 @@ int phy_speed_down_core(struct phy_device *phydev)
return 0;
}

-static void mmd_phy_indirect(struct mii_bus *bus, int phy_addr, int devad,
- u16 regnum)
+static int mmd_phy_indirect(struct mii_bus *bus, int phy_addr, int devad,
+ u16 regnum, bool check_rc)
{
+ int ret;
+
/* Write the desired MMD Devad */
- __mdiobus_write(bus, phy_addr, MII_MMD_CTRL, devad);
+ ret = __mdiobus_write(bus, phy_addr, MII_MMD_CTRL, devad);
+ if (check_rc && ret)
+ return ret;

/* Write the desired MMD register address */
- __mdiobus_write(bus, phy_addr, MII_MMD_DATA, regnum);
+ ret = __mdiobus_write(bus, phy_addr, MII_MMD_DATA, regnum);
+ if (check_rc && ret)
+ return ret;

/* Select the Function : DATA with no post increment */
- __mdiobus_write(bus, phy_addr, MII_MMD_CTRL,
- devad | MII_MMD_CTRL_NOINCR);
+ ret = __mdiobus_write(bus, phy_addr, MII_MMD_CTRL,
+ devad | MII_MMD_CTRL_NOINCR);
+
+ return check_rc ? ret : 0;
+}
+
+/**
+ * __phy_mmd_indirect - prepare an indirect C45 register access
+ *
+ * @bus: the target MII bus
+ * @phy_addr: PHY address on the MII bus
+ * @devad: The target MMD (0..31)
+ * @regnum: The target register on the MMD (0..65535)
+ *
+ * Prepare an indirect C45 read or write transfer using the MII_MMD_CTRL and
+ * MII_MMD_DATA registers in C22 space.
+ */
+int __phy_mmd_indirect(struct mii_bus *bus, int phy_addr, int devad,
+ u16 regnum)
+{
+ return mmd_phy_indirect(bus, phy_addr, devad, regnum, true);
}
+EXPORT_SYMBOL(__phy_mmd_indirect);

/**
* __phy_read_mmd - Convenience function for reading a register
@@ -563,7 +589,7 @@ int __phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum)
struct mii_bus *bus = phydev->mdio.bus;
int phy_addr = phydev->mdio.addr;

- mmd_phy_indirect(bus, phy_addr, devad, regnum);
+ mmd_phy_indirect(bus, phy_addr, devad, regnum, false);

/* Read the content of the MMD's selected register */
val = __mdiobus_read(bus, phy_addr, MII_MMD_DATA);
@@ -619,7 +645,7 @@ int __phy_write_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val)
struct mii_bus *bus = phydev->mdio.bus;
int phy_addr = phydev->mdio.addr;

- mmd_phy_indirect(bus, phy_addr, devad, regnum);
+ mmd_phy_indirect(bus, phy_addr, devad, regnum, false);

/* Write the data into MMD's selected register */
__mdiobus_write(bus, phy_addr, MII_MMD_DATA, val);
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 11c1e91563d4..9521b815d3f0 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -1316,6 +1316,8 @@ int phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum);
__ret; \
})

+int __phy_mmd_indirect(struct mii_bus *bus, int phy_addr, int devad,
+ u16 regnum);
/*
* __phy_read_mmd - Convenience function for reading a register
* from an MMD on a given PHY.

--
2.39.2