From patchwork Mon Dec 12 10:20:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddharth Vadapalli X-Patchwork-Id: 13070912 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 16A05C4332F for ; Mon, 12 Dec 2022 10:22:29 +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=a+hXNc+mTZfhm5HCEYQkudPfYGmo4vRLxuy6XEiar8c=; b=Spd+/tfUO1MNcN +DQnF7TopCtxFZ7MSbt0FVAEXtJ5pglGpq1851CUWGt/V6hkSnsICJ648kb9AgOWeyGgHWtycI7wC pvkZJHQEU9cPNEr56Ae38hBnaxsYHjthH5FVJX5S77v2JpVT5KZiOoNnTKOKkkbwsIQ93oscjnpeT 9FhhUfyx+TIwxgb/brw93I/NgaYO9OpgAnQHT6w4Hi6Bluq1EtvNqu7oAPyKkWwFmtQAXoY/pIgrh +SwgG5j1NdD41TaL/xsLM3t3/rQhcV82f7cotKxcvdDgqXABjUzXha3upvT40fBPvcN6c2MBLl4Em ILJlpB3TQ8cs61Yv7emw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1p4fvk-00Cbwa-0Y; Mon, 12 Dec 2022 10:21:04 +0000 Received: from lelv0142.ext.ti.com ([198.47.23.249]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1p4fvY-00Cbdl-Ek for linux-arm-kernel@lists.infradead.org; Mon, 12 Dec 2022 10:21:00 +0000 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 2BCAKbi0001899; Mon, 12 Dec 2022 04:20:37 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1670840437; bh=eZNdl8Zg2jniUj40iGn+2YXnfest+hfG4/Jhm6+RTH8=; h=From:To:CC:Subject:Date; b=Wy9HhcvzuyVVFD9HCcrpRrliX7tjQs+9YfddOyjSJ8s4CUNSy63Jnm3TAbqAua3wb /1VO3O4FWNRZTE2+c/YIeRVQOJdQ1NJ/snDoCKSHdJPOT56ZShRR9Bfnaik+YelhDM sDo8wtqzvTm7Myjjyl+xR2aBxN043jJN2+212GSE= Received: from DLEE109.ent.ti.com (dlee109.ent.ti.com [157.170.170.41]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 2BCAKbC2081554 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 12 Dec 2022 04:20:37 -0600 Received: from DLEE104.ent.ti.com (157.170.170.34) 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 15.1.2507.16; Mon, 12 Dec 2022 04:20:36 -0600 Received: from lelv0326.itg.ti.com (10.180.67.84) by DLEE104.ent.ti.com (157.170.170.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16 via Frontend Transport; Mon, 12 Dec 2022 04:20:36 -0600 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 2BCAKWGf018094; Mon, 12 Dec 2022 04:20:33 -0600 From: Siddharth Vadapalli To: , , , , , CC: , , , , , , Subject: [PATCH] PCI: cadence: Fix Gen2 Link Retraining process Date: Mon, 12 Dec 2022 15:50:32 +0530 Message-ID: <20221212102032.2063524-1-s-vadapalli@ti.com> X-Mailer: git-send-email 2.25.1 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-20221212_022052_937254_802D2742 X-CRM114-Status: GOOD ( 14.92 ) 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 Link Retraining process is initiated to account for the Gen2 defect in the Cadence PCIe controller in J721E SoC. The errata corresponding to this is i2085, documented at: https://www.ti.com/lit/er/sprz455c/sprz455c.pdf The existing workaround implemented for the errata waits for the Data Link initialization to complete and assumes that the link retraining process at the Physical Layer has completed. However, it is possible that the Physical Layer training might be ongoing as indicated by the PCI_EXP_LNKSTA_LT bit in the PCI_EXP_LNKSTA register. Fix the existing workaround, to ensure that the Physical Layer training has also completed, in addition to the Data Link initialization. Fixes: 4740b969aaf5 ("PCI: cadence: Retrain Link to work around Gen2 training defect") Signed-off-by: Siddharth Vadapalli --- .../controller/cadence/pcie-cadence-host.c | 27 +++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c index 940c7dd701d6..5b14f7ee3c79 100644 --- a/drivers/pci/controller/cadence/pcie-cadence-host.c +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c @@ -12,6 +12,8 @@ #include "pcie-cadence.h" +#define LINK_RETRAIN_TIMEOUT HZ + static u64 bar_max_size[] = { [RP_BAR0] = _ULL(128 * SZ_2G), [RP_BAR1] = SZ_2G, @@ -77,6 +79,27 @@ static struct pci_ops cdns_pcie_host_ops = { .write = pci_generic_config_write, }; +static int cdns_pcie_host_training_complete(struct cdns_pcie *pcie) +{ + u32 pcie_cap_off = CDNS_PCIE_RP_CAP_OFFSET; + unsigned long end_jiffies; + u16 lnk_stat; + + /* Wait for link training to complete. Exit after timeout. */ + end_jiffies = jiffies + LINK_RETRAIN_TIMEOUT; + do { + lnk_stat = cdns_pcie_rp_readw(pcie, pcie_cap_off + PCI_EXP_LNKSTA); + if (!(lnk_stat & PCI_EXP_LNKSTA_LT)) + break; + usleep_range(0, 1000); + } while (time_before(jiffies, end_jiffies)); + + if (!(lnk_stat & PCI_EXP_LNKSTA_LT)) + return 0; + + return -ETIMEDOUT; +} + static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie) { struct device *dev = pcie->dev; @@ -118,6 +141,10 @@ static int cdns_pcie_retrain(struct cdns_pcie *pcie) cdns_pcie_rp_writew(pcie, pcie_cap_off + PCI_EXP_LNKCTL, lnk_ctl); + ret = cdns_pcie_host_training_complete(pcie); + if (ret) + return ret; + ret = cdns_pcie_host_wait_for_link(pcie); } return ret;