Hi,

On 5/26/20 9:31 AM, Russell King wrote:
We have two competing requirements for the devices_in_package field.
We want to use it as a bit array indicating which MMDs are present, but
we also want to know if the Clause 22 registers are present.

Since "devices in package" is a term used in the 802.3 specification,
keep this as the as-specified values read from the PHY, and introduce
a new member "mmds_present" to indicate which MMDs are actually
present in the PHY, derived from the "devices in package" value.

Signed-off-by: Russell King <rmk+ker...@armlinux.org.uk>
---
  drivers/net/phy/phy-c45.c    | 4 ++--
  drivers/net/phy/phy_device.c | 6 +++---
  drivers/net/phy/phylink.c    | 8 ++++----
  include/linux/phy.h          | 4 +++-
  4 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/phy/phy-c45.c b/drivers/net/phy/phy-c45.c
index 8cd952950a75..4b5805e2bd0e 100644
--- a/drivers/net/phy/phy-c45.c
+++ b/drivers/net/phy/phy-c45.c
@@ -219,7 +219,7 @@ int genphy_c45_read_link(struct phy_device *phydev)
        int val, devad;
        bool link = true;
- if (phydev->c45_ids.devices_in_package & MDIO_DEVS_AN) {
+       if (phydev->c45_ids.mmds_present & MDIO_DEVS_AN) {
                val = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_CTRL1);
                if (val < 0)
                        return val;
@@ -397,7 +397,7 @@ int genphy_c45_pma_read_abilities(struct phy_device *phydev)
        int val;
linkmode_clear_bit(ETHTOOL_LINK_MODE_Autoneg_BIT, phydev->supported);
-       if (phydev->c45_ids.devices_in_package & MDIO_DEVS_AN) {
+       if (phydev->c45_ids.mmds_present & MDIO_DEVS_AN) {
                val = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_STAT1);
                if (val < 0)
                        return val;
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index a483d79cfc87..1c948bbf4fa0 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -707,9 +707,6 @@ static int get_phy_c45_devs_in_pkg(struct mii_bus *bus, int 
addr, int dev_addr,
                return -EIO;
        *devices_in_package |= phy_reg;
- /* Bit 0 doesn't represent a device, it indicates c22 regs presence */
-       *devices_in_package &= ~BIT(0);
-
        return 0;
  }
@@ -788,6 +785,8 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id,
        }
c45_ids->devices_in_package = devs_in_pkg;
+       /* Bit 0 doesn't represent a device, it indicates c22 regs presence */
+       c45_ids->mmds_present = devs_in_pkg & ~BIT(0);
*phy_id = 0;
        return 0;
@@ -842,6 +841,7 @@ struct phy_device *get_phy_device(struct mii_bus *bus, int 
addr, bool is_c45)
        int r;
c45_ids.devices_in_package = 0;
+       c45_ids.mmds_present = 0;
        memset(c45_ids.device_ids, 0xff, sizeof(c45_ids.device_ids));
if (is_c45)
diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 6defd5eddd58..b548e0418694 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1709,11 +1709,11 @@ static int phylink_phy_read(struct phylink *pl, 
unsigned int phy_id,
                case MII_BMSR:
                case MII_PHYSID1:
                case MII_PHYSID2:
-                       devad = __ffs(phydev->c45_ids.devices_in_package);
+                       devad = __ffs(phydev->c45_ids.mmds_present);
                        break;
                case MII_ADVERTISE:
                case MII_LPA:
-                       if (!(phydev->c45_ids.devices_in_package & 
MDIO_DEVS_AN))
+                       if (!(phydev->c45_ids.mmds_present & MDIO_DEVS_AN))
                                return -EINVAL;
                        devad = MDIO_MMD_AN;
                        if (reg == MII_ADVERTISE)
@@ -1749,11 +1749,11 @@ static int phylink_phy_write(struct phylink *pl, 
unsigned int phy_id,
                case MII_BMSR:
                case MII_PHYSID1:
                case MII_PHYSID2:
-                       devad = __ffs(phydev->c45_ids.devices_in_package);
+                       devad = __ffs(phydev->c45_ids.mmds_present);
                        break;
                case MII_ADVERTISE:
                case MII_LPA:
-                       if (!(phydev->c45_ids.devices_in_package & 
MDIO_DEVS_AN))
+                       if (!(phydev->c45_ids.mmds_present & MDIO_DEVS_AN))
                                return -EINVAL;
                        devad = MDIO_MMD_AN;
                        if (reg == MII_ADVERTISE)
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 41c046545354..0d41c710339a 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -354,11 +354,13 @@ enum phy_state {
/**
   * struct phy_c45_device_ids - 802.3-c45 Device Identifiers
- * @devices_in_package: Bit vector of devices present.
+ * @devices_in_package: IEEE 802.3 devices in package register value.
+ * @mmds_present: bit vector of MMDs present.
   * @device_ids: The device identifer for each present device.
   */
  struct phy_c45_device_ids {
        u32 devices_in_package;
+       u32 mmds_present;
        u32 device_ids[8];
  };

It seems like the majority of the devices_in_package accessors are just bit masking for a given MMD/field. The case that has the problem is the __ffs() calls which failed to account for this. So why not just fix those two cases instead of creating a duplicate field with exactly the same data in it minus a bit.





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