From patchwork Wed Mar 13 21:37:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Remi Pommarel X-Patchwork-Id: 10851853 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ABF3314DE for ; Wed, 13 Mar 2019 21:29:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98D8829BBF for ; Wed, 13 Mar 2019 21:29:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8C89229BCE; Wed, 13 Mar 2019 21:29:26 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D4EC029CED for ; Wed, 13 Mar 2019 21:29:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727391AbfCMV3U (ORCPT ); Wed, 13 Mar 2019 17:29:20 -0400 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:57321 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726772AbfCMV3T (ORCPT ); Wed, 13 Mar 2019 17:29:19 -0400 X-Originating-IP: 88.190.179.123 Received: from localhost (unknown [88.190.179.123]) (Authenticated sender: repk@triplefau.lt) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id 74E1860003; Wed, 13 Mar 2019 21:29:16 +0000 (UTC) From: Remi Pommarel To: Thomas Petazzoni , Lorenzo Pieralisi , Bjorn Helgaas Cc: linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Miquel Raynal , Remi Pommarel Subject: [PATCH] pci: aardvark: Wait for endpoint to be ready before training link Date: Wed, 13 Mar 2019 22:37:52 +0100 Message-Id: <20190313213752.1246-1-repk@triplefau.lt> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When configuring pcie reset pin from gpio (e.g. initially set by u-boot) to pcie function this pin goes low for a brief moment asserting the PERST# signal. Thus connected device enters fundamental reset process and link configuration can only begin after a minimal 100ms delay (see [1]). This makes sure that link is configured after at least 100ms from beginning of probe() callback (shortly after the reset pin function configuration switch through pinctrl subsytem). [1] "PCI Express Base Specification", REV. 2.1 PCI Express, March 4 2009, 6.6.1 Conventional Reset Signed-off-by: Remi Pommarel --- drivers/pci/controller/pci-aardvark.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c index a30ae7cf8e7e..70a1023d0ef1 100644 --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -177,6 +177,9 @@ #define PIO_TIMEOUT_MS 1 +/* Endpoint can take up to 100ms to be ready after a reset */ +#define ENDPOINT_RST_MS 100 + #define LINK_WAIT_MAX_RETRIES 10 #define LINK_WAIT_USLEEP_MIN 90000 #define LINK_WAIT_USLEEP_MAX 100000 @@ -242,8 +245,10 @@ static int advk_pcie_wait_for_link(struct advk_pcie *pcie) return -ETIMEDOUT; } -static void advk_pcie_setup_hw(struct advk_pcie *pcie) +static void +advk_pcie_setup_hw(struct advk_pcie *pcie, unsigned long ep_rdy_time) { + unsigned long now; u32 reg; /* Set to Direct mode */ @@ -327,9 +332,12 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie) reg |= PIO_CTRL_ADDR_WIN_DISABLE; advk_writel(pcie, reg, PIO_CTRL); - /* Start link training */ + /* Wait for endpoint to exit reset state and start link training */ reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG); reg |= PCIE_CORE_LINK_TRAINING; + now = jiffies; + if (time_before(now, ep_rdy_time)) + msleep(jiffies_to_msecs(ep_rdy_time - now)); advk_writel(pcie, reg, PCIE_CORE_LINK_CTRL_STAT_REG); advk_pcie_wait_for_link(pcie); @@ -993,8 +1001,11 @@ static int advk_pcie_probe(struct platform_device *pdev) struct advk_pcie *pcie; struct resource *res; struct pci_host_bridge *bridge; + unsigned long ep_rdy_time; int ret, irq; + ep_rdy_time = jiffies + msecs_to_jiffies(ENDPOINT_RST_MS); + bridge = devm_pci_alloc_host_bridge(dev, sizeof(struct advk_pcie)); if (!bridge) return -ENOMEM; @@ -1022,7 +1033,7 @@ static int advk_pcie_probe(struct platform_device *pdev) return ret; } - advk_pcie_setup_hw(pcie); + advk_pcie_setup_hw(pcie, ep_rdy_time); advk_sw_pci_bridge_init(pcie);