From patchwork Tue Sep 26 05:42:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddharth Vadapalli X-Patchwork-Id: 13398673 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 603FCE7D0C5 for ; Tue, 26 Sep 2023 05:42:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233170AbjIZFm0 (ORCPT ); Tue, 26 Sep 2023 01:42:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233641AbjIZFmZ (ORCPT ); Tue, 26 Sep 2023 01:42:25 -0400 Received: from fllv0015.ext.ti.com (fllv0015.ext.ti.com [198.47.19.141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6994F2; Mon, 25 Sep 2023 22:42:18 -0700 (PDT) Received: from lelv0265.itg.ti.com ([10.180.67.224]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 38Q5g4BW113394; Tue, 26 Sep 2023 00:42:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1695706925; bh=FaCNcoOxk7RfK05IOQkkeblKCAra5walu+sg3plROtg=; h=From:To:CC:Subject:Date; b=Kxpf4qUl1lF6Bw5TjwUVKUc6cX34jvzW/lbgdXmi4UdajLR3G2WkXeYDpmWez/gSN iO2FLEIImJDJA0l+JD7ZXK+pNpjfffIcsrMyy8Jgd8VV379QQtWylR+lGnRjm1Sa/W Ek73aaCM22aeZLGstxCQR3avG6kmx4sYUdtW58r8= Received: from DLEE103.ent.ti.com (dlee103.ent.ti.com [157.170.170.33]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 38Q5g43j012577 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 26 Sep 2023 00:42:04 -0500 Received: from DLEE109.ent.ti.com (157.170.170.41) by DLEE103.ent.ti.com (157.170.170.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.23; Tue, 26 Sep 2023 00:42:04 -0500 Received: from fllv0040.itg.ti.com (10.64.41.20) by DLEE109.ent.ti.com (157.170.170.41) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.23 via Frontend Transport; Tue, 26 Sep 2023 00:42:04 -0500 Received: from uda0492258.dhcp.ti.com (ileaxei01-snat.itg.ti.com [10.180.69.5]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id 38Q5g0AA033333; Tue, 26 Sep 2023 00:42:01 -0500 From: Siddharth Vadapalli To: , , , CC: , , , , , , Subject: [PATCH] PCI: keystone: Fix race condition when initializing PHYs Date: Tue, 26 Sep 2023 11:12:00 +0530 Message-ID: <20230926054200.963803-1-s-vadapalli@ti.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org The PCI driver invokes the PHY APIs using the ks_pcie_enable_phy() function. The PHY in this case is the Serdes. It is possible that the PCI instance is configured for 2 lane operation across two different Serdes instances, using 1 lane of each Serdes. In such a configuration, if the reference clock for one Serdes is provided by the other Serdes, it results in a race condition. After the Serdes providing the reference clock is initialized by the PCI driver by invoking its PHY APIs, it is not guaranteed that this Serdes remains powered on long enough for the PHY APIs based initialization of the dependent Serdes. In such cases, the PLL of the dependent Serdes fails to lock due to the absence of the reference clock from the former Serdes which has been powered off by the PM Core. Fix this by obtaining reference to the PHYs before invoking the PHY initialization APIs and releasing reference after the initialization is complete. Fixes: 49229238ab47 ("PCI: keystone: Cleanup PHY handling") Signed-off-by: Siddharth Vadapalli --- drivers/pci/controller/dwc/pci-keystone.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c index 49aea6ce3e87..526b68100a4a 100644 --- a/drivers/pci/controller/dwc/pci-keystone.c +++ b/drivers/pci/controller/dwc/pci-keystone.c @@ -1218,12 +1218,20 @@ static int __init ks_pcie_probe(struct platform_device *pdev) goto err_link; } + /* Obtain reference(s) to the phy(s) */ + for (i = 0; i < num_lanes; i++) + phy_pm_runtime_get_sync(ks_pcie->phy[i]); + ret = ks_pcie_enable_phy(ks_pcie); if (ret) { dev_err(dev, "failed to enable phy\n"); goto err_link; } + /* Release reference(s) to the phy(s) */ + for (i = 0; i < num_lanes; i++) + phy_pm_runtime_put_sync(ks_pcie->phy[i]); + platform_set_drvdata(pdev, ks_pcie); pm_runtime_enable(dev); ret = pm_runtime_get_sync(dev);