Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753150AbdLEN1S (ORCPT ); Tue, 5 Dec 2017 08:27:18 -0500 Received: from relay14.alfahosting-server.de ([109.237.142.228]:40992 "EHLO relay14.alfahosting-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752592AbdLEN0m (ORCPT ); Tue, 5 Dec 2017 08:26:42 -0500 X-Spam-DCC: : From: Richard Leitner To: robh+dt@kernel.org, mark.rutland@arm.com, fugang.duan@nxp.com, andrew@lunn.ch, f.fainelli@gmail.com, frowand.list@gmail.com Cc: davem@davemloft.net, geert+renesas@glider.be, sergei.shtylyov@cogentembedded.com, baruch@tkos.co.il, david.wu@rock-chips.com, lukma@denx.de, netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, richard.leitner@skidata.com Subject: [PATCH net-next v3 4/4] net: fec: add phy_reset_after_clk_enable() support Date: Tue, 5 Dec 2017 14:26:00 +0100 Message-Id: <20171205132600.13796-5-dev@g0hl1n.net> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20171205132600.13796-1-dev@g0hl1n.net> References: <20171205132600.13796-1-dev@g0hl1n.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2186 Lines: 53 From: Richard Leitner Some PHYs (for example the SMSC LAN8710/LAN8720) doesn't allow turning the refclk on and off again during operation (according to their datasheet). Nonetheless exactly this behaviour was introduced for power saving reasons by commit e8fcfcd5684a ("net: fec: optimize the clock management to save power"). Therefore add support for the phy_reset_after_clk_enable function from phylib to mitigate this issue. Generally speaking this issue is only relevant if the ref clk for the PHY is generated by the SoC and therefore the PHY is configured to "REF_CLK In Mode". In our specific case (PCB) this problem does occur at about every 10th to 50th POR of an LAN8710 connected to an i.MX6SOLO SoC. The typical symptom of this problem is a "swinging" ethernet link. Similar issues were reported by users of the NXP forum: https://community.nxp.com/thread/389902 https://community.nxp.com/message/309354 With this patch applied the issue didn't occur for at least a few hundret PORs of our board. Fixes: e8fcfcd5684a ("net: fec: optimize the clock management to save power") Signed-off-by: Richard Leitner --- drivers/net/ethernet/freescale/fec_main.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 610573855213..8c3d0fb7db20 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -1862,6 +1862,8 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable) ret = clk_prepare_enable(fep->clk_ref); if (ret) goto failed_clk_ref; + + phy_reset_after_clk_enable(ndev->phydev); } else { clk_disable_unprepare(fep->clk_ahb); clk_disable_unprepare(fep->clk_enet_out); @@ -2860,6 +2862,11 @@ fec_enet_open(struct net_device *ndev) if (ret) goto err_enet_mii_probe; + /* reset phy if needed here, due to the fact this is the first time we + * have the net_device to phy_driver link + */ + phy_reset_after_clk_enable(ndev->phydev); + if (fep->quirks & FEC_QUIRK_ERR006687) imx6q_cpuidle_fec_irqs_used(); -- 2.11.0