From: Russell King Subject: [PATCH] net: phy: marvell: avoid pause mode on SGMII-to-Copper for 88e151x Date: Fri, 15 Dec 2017 16:10:20 +0000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Cc: netdev@vger.kernel.org To: Andrew Lunn , Florian Fainelli Return-path: Received: from pandora.armlinux.org.uk ([78.32.30.218]:39378 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932549AbdLOQKX (ORCPT ); Fri, 15 Dec 2017 11:10:23 -0500 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Observed on the 88e1512 in SGMII-to-Copper mode, negotiating pause is unreliable. While the pause bits can be set in the advertisment register, they clear shortly after negotiation with a link partner commences irrespective of the cause of the negotiation. While these bits may be correctly conveyed to the link partner on the first negotiation, a subsequent negotiation (eg, due to negotiation restart by the link partner, or reconnection of the cable) will result in the link partner seeing these bits as zero, while the kernel believes that it has advertised pause modes. This leads to the local kernel evaluating (eg) symmetric pause mode, while the remote end evaluates that we have no pause mode capability. Since we can't guarantee the advertisment, disable pause mode support with this PHY when used in SGMII-to-Copper mode. The 88e1510 in RGMII-to-Copper mode appears to behave correctly. Reviewed-by: Andrew Lunn Signed-off-by: Russell King --- drivers/net/phy/marvell.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c index b5a8f750e433..2510acc0feb0 100644 --- a/drivers/net/phy/marvell.c +++ b/drivers/net/phy/marvell.c @@ -879,6 +879,8 @@ static int m88e1510_config_init(struct phy_device *phydev) /* SGMII-to-Copper mode initialization */ if (phydev->interface == PHY_INTERFACE_MODE_SGMII) { + u32 pause; + /* Select page 18 */ err = marvell_set_page(phydev, 18); if (err < 0) @@ -902,6 +904,16 @@ static int m88e1510_config_init(struct phy_device *phydev) err = marvell_set_page(phydev, MII_MARVELL_COPPER_PAGE); if (err < 0) return err; + + /* There appears to be a bug in the 88e1512 when used in + * SGMII to copper mode, where the AN advertisment register + * clears the pause bits each time a negotiation occurs. + * This means we can never be truely sure what was advertised, + * so disable Pause support. + */ + pause = SUPPORTED_Pause | SUPPORTED_Asym_Pause; + phydev->supported &= ~pause; + phydev->advertising &= ~pause; } return m88e1121_config_init(phydev); -- 2.7.4