From patchwork Tue Sep 26 06:36:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddharth Vadapalli X-Patchwork-Id: 13398775 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5E40CEE020C for ; Tue, 26 Sep 2023 06:37:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:CC :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=hVX2vxHvEAnbZZvHNKoBNUVQ0DfDXJf5bIjoFTzEN+s=; b=v6rw8FG11fk8DS hVqNvbnwwez+ZpVm/deuB7Y+1a+na49lrpoOBU/PPf/jyklq/bYWUmwWVG1935Jp0efM3hsAH/u3q 7OkIIluG4Z+XMNFhcpITRKBcbXw0rCzwpNtus7onHuKzFZbcyyIDeaWvhPuouvQCEyhxeA/1P/bG7 cHnehmAGUQIY8/xfOnrb6lThgOEVirFh5lA20bw/CX5vCEf3KZaGvZQS3U7RlwBbCaQ4TwtMAgTml HJhrjkw43RAHfESMHQodUTZZO/LLgFNYXUf0nsdcmvSlBlVt26z4PkIUXwPVghRw9+oyj/VThZQ1p LceWtPFWDiBjwHSNn8LA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1ql1gn-00FjWU-2T; Tue, 26 Sep 2023 06:36:57 +0000 Received: from lelv0143.ext.ti.com ([198.47.23.248]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1ql1gk-00FjUu-1a for linux-arm-kernel@lists.infradead.org; Tue, 26 Sep 2023 06:36:56 +0000 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by lelv0143.ext.ti.com (8.15.2/8.15.2) with ESMTP id 38Q6aheP079982; Tue, 26 Sep 2023 01:36:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1695710203; bh=FGTt6eLB4oWILXc84fH5qn5fVFwcTXa3+q1FG3J3WFI=; h=From:To:CC:Subject:Date; b=SY8If1Yw83kP8SripQaV9umxbvHJZhSsg+otzKiGFSWdSgSgnvFg5P13DPfLEXjD1 3qyBK4//o0AgpR9uM5iTWMSGyPrbI0v3ran3b+EqAegJdClaqD7T/Q68t1H4dofQ63 NoXDHU8GvNmW9dzQP2nsm5LVdRb8njCDQhF2vN34= Received: from DFLE104.ent.ti.com (dfle104.ent.ti.com [10.64.6.25]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 38Q6ahBp066236 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 26 Sep 2023 01:36:43 -0500 Received: from DFLE115.ent.ti.com (10.64.6.36) by DFLE104.ent.ti.com (10.64.6.25) 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 01:36:42 -0500 Received: from lelv0326.itg.ti.com (10.180.67.84) by DFLE115.ent.ti.com (10.64.6.36) 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 01:36:42 -0500 Received: from uda0492258.dhcp.ti.com (ileaxei01-snat.itg.ti.com [10.180.69.5]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id 38Q6adwB010320; Tue, 26 Sep 2023 01:36:39 -0500 From: Siddharth Vadapalli To: , , , CC: , , , , , , Subject: [PATCH v2] PCI: keystone: Fix race condition when initializing PHYs Date: Tue, 26 Sep 2023 12:06:38 +0530 Message-ID: <20230926063638.1005124-1-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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230925_233654_609953_B2BAA929 X-CRM114-Status: GOOD ( 15.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 --- NOTE: This patch is based on linux-next tagged next-20230925. v1: https://lore.kernel.org/r/20230926054200.963803-1-s-vadapalli@ti.com/ Changes since v1: - Add code to release reference(s) to the phy(s) when ks_pcie_enable_phy(ks_pcie) fails. Regards, Siddharth. drivers/pci/controller/dwc/pci-keystone.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c index 49aea6ce3e87..e4d43306a7e3 100644 --- a/drivers/pci/controller/dwc/pci-keystone.c +++ b/drivers/pci/controller/dwc/pci-keystone.c @@ -1218,12 +1218,24 @@ 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"); + /* Release reference(s) to the phy(s) */ + for (i = 0; i < num_lanes; i++) + phy_pm_runtime_put_sync(ks_pcie->phy[i]); + 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);