From patchwork Mon May 31 09:05:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Ceresoli X-Patchwork-Id: 450644 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B4C4C47082 for ; Mon, 31 May 2021 09:06:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D80B560FDA for ; Mon, 31 May 2021 09:06:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230400AbhEaJHo (ORCPT ); Mon, 31 May 2021 05:07:44 -0400 Received: from hostingweb31-40.netsons.net ([89.40.174.40]:41694 "EHLO hostingweb31-40.netsons.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229945AbhEaJHk (ORCPT ); Mon, 31 May 2021 05:07:40 -0400 Received: from [77.244.183.192] (port=63384 helo=melee.fritz.box) by hostingweb31.netsons.net with esmtpa (Exim 4.94.2) (envelope-from ) id 1lndrr-0009Gk-0d; Mon, 31 May 2021 11:05:51 +0200 From: Luca Ceresoli To: linux-pci@vger.kernel.org Cc: Luca Ceresoli , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Kishon Vijay Abraham I , Lorenzo Pieralisi , Rob Herring , Bjorn Helgaas Subject: [PATCH v2] PCI: dra7xx: Fix reset behaviour Date: Mon, 31 May 2021 11:05:40 +0200 Message-Id: <20210531090540.2663171-1-luca@lucaceresoli.net> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - hostingweb31.netsons.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lucaceresoli.net X-Get-Message-Sender-Via: hostingweb31.netsons.net: authenticated_id: luca+lucaceresoli.net/only user confirmed/virtual account not confirmed X-Authenticated-Sender: hostingweb31.netsons.net: luca@lucaceresoli.net X-Source: X-Source-Args: X-Source-Dir: Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org The PCIe PERSTn reset pin is active low and should be asserted, then deasserted. The current implementation only drives the pin once in "HIGH" position, thus presumably it was intended to deassert the pin. This has two problems: 1) it assumes the pin was asserted by other means before loading the driver 2) it has the wrong polarity, since "HIGH" means "active", and the pin is presumably configured as active low coherently with the PCIe convention, thus it is driven physically to 0, keeping the device under reset unless the pin is configured as active high. Fix both problems by: 1) keeping devm_gpiod_get_optional(dev, NULL, GPIOD_OUT_HIGH) as is, but assuming the pin is correctly configured as "active low" this now becomes a reset assertion 2) adding gpiod_set_value(reset, 0) after a delay to deassert reset Fixes: 78bdcad05ea1 ("PCI: dra7xx: Add support to make GPIO drive PERST# line") Signed-off-by: Luca Ceresoli --- Changes v1 -> v2: - No changes to the patch - Reword commit message according to suggestions from Bjorn Helgaas (from another patchset) - Add Fixes: tag --- drivers/pci/controller/dwc/pci-dra7xx.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/pci/controller/dwc/pci-dra7xx.c b/drivers/pci/controller/dwc/pci-dra7xx.c index cb5d4c245ff6..11f392b7a9a2 100644 --- a/drivers/pci/controller/dwc/pci-dra7xx.c +++ b/drivers/pci/controller/dwc/pci-dra7xx.c @@ -801,6 +801,8 @@ static int dra7xx_pcie_probe(struct platform_device *pdev) dev_err(&pdev->dev, "gpio request failed, ret %d\n", ret); goto err_gpio; } + usleep_range(1000, 2000); + gpiod_set_value(reset, 0); reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_DEVICE_CMD); reg &= ~LTSSM_EN;