Re: [PATCH v2 3/3] net/phy: micrel: Center FLP timing at 16ms

[Sergei Shtylyov]

Hello.

On 06/05/2015 10:55 PM, Jaeden Amero wrote:

Link failures have been observed when using the KSZ9031 with HP 1810-8G
and HP 1910-8G network switches. Center the FLP timing at 16ms to help
avoid intermittent link failures.

 From the KSZ9031RNX and KSZ9031MNX data sheets revision 2.2, section
"Auto-Negotiation Timing":
        The KSZ9031[RNX or MNX] Fast Link Pulse (FLP) burst-to-burst
        transmit timing for Auto-Negotiation defaults to 8ms. IEEE 802.3
        Standard specifies this timing to be 16ms +/-8ms. Some PHY link
        partners need to receive the FLP with 16ms centered timing;
        otherwise, there can be intermittent link failures and long
        link-up times.

        After KSZ9031[RNX or MNX] power-up/reset, program the following
        register sequence to set the FLP timing to 16ms

        Write Register Dh = 0x0000 // Set up register address for MMD – Device 
Address 0h
        Write Register Eh = 0x0004 // Select Register 4h of MMD – Device 
Address 0h
        Write Register Dh = 0x4000 // Select register data for MMD – Device 
Address 0h, Register 4h
        Write Register Eh = 0x0006 // Write value 0x0006 to MMD – Device 
Address 0h, Register 4h
        Write Register Dh = 0x0000 // Set up register address for MMD – Device 
Address 0h
        Write Register Eh = 0x0003 // Select Register 3h of MMD – Device 
Address 0h
        Write Register Dh = 0x4000 // Select register data for MMD – Device 
Address 0h, Register 3h
        Write Register Eh = 0x1A80 // Write value 0x1A80 to MMD – Device 
Address 0h, Register 3h
        Write Register 0h, Bit [9] = 1 // Restart Auto-Negotiation

Signed-off-by: Jaeden Amero <jaeden.am...@ni.com>
---
  drivers/net/phy/micrel.c | 26 +++++++++++++++++++++++++-
  1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index f23765e..e156e36 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c

[...]

@@ -441,6 +461,7 @@ static int ksz9031_config_init(struct phy_device *phydev)
                "txd2-skew-ps", "txd3-skew-ps"
        };
        static const char *control_skews[2] = {"txen-skew-ps", "rxdv-skew-ps"};
+       int result;

   You hardly need this variable...

        if (!of_node && dev->parent->of_node)
                of_node = dev->parent->of_node;
@@ -462,7 +483,10 @@ static int ksz9031_config_init(struct phy_device *phydev)
                                MII_KSZ9031RN_TX_DATA_PAD_SKEW, 4,
                                tx_data_skews, 4);
        }
-       return 0;
+
+       result = ksz9031_center_flp_timing(phydev);
+
+       return result;

   Why not just return directly?

[...]

WBR, Sergei

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