From patchwork Mon Jan 2 07:56:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddharth Vadapalli X-Patchwork-Id: 13086566 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 C9B3AC4167B for ; Mon, 2 Jan 2023 08:00:05 +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=CgD5x23k+evGqF FuP5Gqy1aCl+FtAOX5VOHtQqx0zegpntkWOZxgR6nOrpSmDtvlsCpntcDHnJVFYyZAZ+CtkIl4QUN v7cbqROnoT6VlzLxpUp7/+ld9zHQV+OX30/GlhcaNIQRXEuVcbQxvJF0Bq3cu3CGHFHGBs2ggAdsX I1tDW4vHLAzRqtn/R+c/A0YO6gXPx4+9XJqYTtD4HONh81b8Fg4/SkxHLLYaWxJbQdUTwHnkMaCUc AcfSBLfbf7ydzXFMXeLcnyoncviH5s4NzwuVlzsFZBpNIYseGsg4PdWczPt6p7IDX3S9/gwqhhoEI Sq0wmgCG5EG/03ewUhtQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pCFiR-009II7-Vy; Mon, 02 Jan 2023 07:58:40 +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 1pCFh8-009I0Y-66 for linux-arm-kernel@lists.infradead.org; Mon, 02 Jan 2023 07:57:20 +0000 Received: from lelv0266.itg.ti.com ([10.180.67.225]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 3027v12q122744; Mon, 2 Jan 2023 01:57:01 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1672646221; bh=eZNdl8Zg2jniUj40iGn+2YXnfest+hfG4/Jhm6+RTH8=; h=From:To:CC:Subject:Date; b=oeImrmQUaMmLCEZG+eMls7OYNh2Os/OFBaoOyapVxSTzRFZkIfTGBOhJhfayCg2T4 yqIBpcsA/sTl8a7GqsNnM3P19ecvRzZaXz/6IrD/lvW5lGZppZOB6mElSim9KAytvD e3aV3gulvkTBdQIgn/8bqj0Mo4iHoUaitp2IUnPo= Received: from DFLE105.ent.ti.com (dfle105.ent.ti.com [10.64.6.26]) by lelv0266.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 3027v1XI105780 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 2 Jan 2023 01:57:01 -0600 Received: from DFLE103.ent.ti.com (10.64.6.24) by DFLE105.ent.ti.com (10.64.6.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.16; Mon, 2 Jan 2023 01:57:00 -0600 Received: from fllv0040.itg.ti.com (10.64.41.20) by DFLE103.ent.ti.com (10.64.6.24) 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, 2 Jan 2023 01:57:00 -0600 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 3027uuJD021994; Mon, 2 Jan 2023 01:56:57 -0600 From: Siddharth Vadapalli To: , , , , , CC: , , , , , , Subject: [RESEND PATCH] PCI: cadence: Fix Gen2 Link Retraining process Date: Mon, 2 Jan 2023 13:26:56 +0530 Message-ID: <20230102075656.260333-1-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-20230101_235718_450546_7538E23C X-CRM114-Status: GOOD ( 15.91 ) 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 Reviewed-by: Vignesh Raghavendra --- .../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;