From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E2FEC2BA19 for ; Wed, 15 Apr 2020 11:56:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08CE1206A2 for ; Wed, 15 Apr 2020 11:56:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586951791; bh=RcHhJ91AHTGJVw8sl+DGn5fvCtyzvZPESe/szQp5q28=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1XfCZdySgN2hFj2TDMzGygT0CzgvTwTZU+pFJooW+Fny0q2QlCUiIlUsCqVBsGDyd KjNUER3eP7PYP6vrgDwalaiWg7UTwjFBMMisM5mAMYkDxbU2iImaSuuv8FqEdNhd6K RCs+8pnrJKIoLAB+uVFqq21t/C/RMRT9tOk2xu/8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409642AbgDOL43 (ORCPT ); Wed, 15 Apr 2020 07:56:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:40340 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2409229AbgDOLpz (ORCPT ); Wed, 15 Apr 2020 07:45:55 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 408332078A; Wed, 15 Apr 2020 11:45:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586951153; bh=RcHhJ91AHTGJVw8sl+DGn5fvCtyzvZPESe/szQp5q28=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m7d6/HCiGL23DSORdTXomRJvhwLIZ2VJlODGEmWCChblFQOkEBbHUjhQ0JsWNoVP/ qyhGgv5mkZtQSVqnzqdj61FfFyqUkFfeVtErqM6pqFK74qDgFw1KgHelSSoYGQ7Ctp rXe9KJXnV1d2X4wWZ2OT5o7OTZaJ3jsUHrNt3vyA= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Oleksij Rempel , Andrew Lunn , Florian Fainelli , "David S . Miller" , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 59/84] net: phy: micrel: kszphy_resume(): add delay after genphy_resume() before accessing PHY registers Date: Wed, 15 Apr 2020 07:44:16 -0400 Message-Id: <20200415114442.14166-59-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200415114442.14166-1-sashal@kernel.org> References: <20200415114442.14166-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleksij Rempel [ Upstream commit 6110dff776f7fa65c35850ef65b41d3b39e2fac2 ] After the power-down bit is cleared, the chip internally triggers a global reset. According to the KSZ9031 documentation, we have to wait at least 1ms for the reset to finish. If the chip is accessed during reset, read will return 0xffff, while write will be ignored. Depending on the system performance and MDIO bus speed, we may or may not run in to this issue. This bug was discovered on an iMX6QP system with KSZ9031 PHY and attached PHY interrupt line. If IRQ was used, the link status update was lost. In polling mode, the link status update was always correct. The investigation showed, that during a read-modify-write access, the read returned 0xffff (while the chip was still in reset) and corresponding write hit the chip _after_ reset and triggered (due to the 0xffff) another reset in an undocumented bit (register 0x1f, bit 1), resulting in the next write being lost due to the new reset cycle. This patch fixes the issue by adding a 1...2 ms sleep after the genphy_resume(). Fixes: 836384d2501d ("net: phy: micrel: Add specific suspend") Signed-off-by: Oleksij Rempel Reviewed-by: Andrew Lunn Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/phy/micrel.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c index 63dedec0433de..51b64f0877172 100644 --- a/drivers/net/phy/micrel.c +++ b/drivers/net/phy/micrel.c @@ -25,6 +25,7 @@ #include #include #include +#include /* Operation Mode Strap Override */ #define MII_KSZPHY_OMSO 0x16 @@ -902,6 +903,12 @@ static int kszphy_resume(struct phy_device *phydev) genphy_resume(phydev); + /* After switching from power-down to normal mode, an internal global + * reset is automatically generated. Wait a minimum of 1 ms before + * read/write access to the PHY registers. + */ + usleep_range(1000, 2000); + ret = kszphy_config_reset(phydev); if (ret) return ret; -- 2.20.1