diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/phy/micrel.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c index f41b224a9cdb..ab195f0916d6 100644 --- a/drivers/net/phy/micrel.c +++ b/drivers/net/phy/micrel.c @@ -573,9 +573,40 @@ static int ksz9031_config_init(struct phy_device *phydev) ksz9031_of_load_skew_values(phydev, of_node, MII_KSZ9031RN_TX_DATA_PAD_SKEW, 4, tx_data_skews, 4); + + /* Silicon Errata Sheet (DS80000691D or DS80000692D): + * When the device links in the 1000BASE-T slave mode only, + * the optional 125MHz reference output clock (CLK125_NDO) + * has wide duty cycle variation. + * + * The optional CLK125_NDO clock does not meet the RGMII + * 45/55 percent (min/max) duty cycle requirement and therefore + * cannot be used directly by the MAC side for clocking + * applications that have setup/hold time requirements on + * rising and falling clock edges. + * + * Workaround: + * Force the phy to be the master to receive a stable clock + * which meets the duty cycle requirement. + */ + if (of_property_read_bool(of_node, "micrel,force-master")) { + result = phy_read(phydev, MII_CTRL1000); + if (result < 0) + goto err_force_master; + + /* enable master mode, config & prefer master */ + result |= CTL1000_ENABLE_MASTER | CTL1000_AS_MASTER; + result = phy_write(phydev, MII_CTRL1000, result); + if (result < 0) + goto err_force_master; + } } return ksz9031_center_flp_timing(phydev); + +err_force_master: + phydev_err(phydev, "failed to force the phy to master mode\n"); + return result; } #define KSZ8873MLL_GLOBAL_CONTROL_4 0x06 |