diff options
Diffstat (limited to 'target/linux/mvebu/patches-4.9/409-net-phy-don-t-double-read-clause-45-status-register.patch')
| -rw-r--r-- | target/linux/mvebu/patches-4.9/409-net-phy-don-t-double-read-clause-45-status-register.patch | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/target/linux/mvebu/patches-4.9/409-net-phy-don-t-double-read-clause-45-status-register.patch b/target/linux/mvebu/patches-4.9/409-net-phy-don-t-double-read-clause-45-status-register.patch new file mode 100644 index 0000000000..ee53fe0380 --- /dev/null +++ b/target/linux/mvebu/patches-4.9/409-net-phy-don-t-double-read-clause-45-status-register.patch @@ -0,0 +1,35 @@ +From: Russell King <rmk+kernel@armlinux.org.uk> +Date: Thu, 5 Jan 2017 00:23:40 +0000 +Subject: [PATCH] net: phy: don't double-read clause 45 status register + +One of the design decisions behind the link status bit in the status +register is that it latches low on link loss. This is so that link loss +events are not missed. Double-reading the status register means that we +always read the current state of the link, clearing any link loss event. + +This can cause problems - for example, if the link has negotiated a +different set of operating parameters, these will not be communicated +to the MAC as the PHY state machine will still think that the link has +remained active. + +Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> +--- + +--- a/drivers/net/phy/phy-c45.c ++++ b/drivers/net/phy/phy-c45.c +@@ -143,12 +143,9 @@ int genphy_c45_read_link(struct phy_devi + devad = __ffs(mmd_mask); + mmd_mask &= ~BIT(devad); + +- val = phy_read_mmd(phydev, devad, MDIO_STAT1); +- if (val < 0) +- return val; +- +- /* Read twice because link state is latched and a +- * read moves the current state into the register ++ /* The link state is latched low so that momentary link ++ * drops can be detected. Do not double-read the status ++ * register if the link is down. + */ + val = phy_read_mmd(phydev, devad, MDIO_STAT1); + if (val < 0) |