From mboxrd@z Thu Jan 1 00:00:00 1970 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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 EE36CCA9EBD for ; Fri, 25 Oct 2019 19:17:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C3E5C20679 for ; Fri, 25 Oct 2019 19:17:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cDRuooQ7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726720AbfJYTRM (ORCPT ); Fri, 25 Oct 2019 15:17:12 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:46695 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725783AbfJYTRM (ORCPT ); Fri, 25 Oct 2019 15:17:12 -0400 Received: by mail-pg1-f195.google.com with SMTP id f19so2129407pgn.13; Fri, 25 Oct 2019 12:17:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=CQ/0y5Q6U9cve/rqfcOyl2Y7XrZFSX/kWDN3gMk9jY0=; b=cDRuooQ7ESXeuKARMwPhRSPK81ZuqJ3KGR+tYRw3ElchzVawLyMafPX5ShC5MbXQut PP4CMYeFmn64xJs3hYF5C/zSkOeAs+nvpQPoqf4Yt1f8eeEJVuLO/9lnP1u65h8E1Hku 6fqXpBKhw/KXPgqOfMd/TbTJIaZv+dtNv/2HJFwxWHsvvFTzMBL7XlcuDnHhONkM50jJ oKsiy2cgZRjsvoYb9fBbVvCSJCeWP5cdoAqics6asWLT4QLBqDF2q86UX+YYYAVLJs9u CEvKBuQMASnzV3jinpz+/cEAvDQKtKRiUDoQkeaS0oGUD2Lfe4Ox/j5wr51yVIXbh44Q zHGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=CQ/0y5Q6U9cve/rqfcOyl2Y7XrZFSX/kWDN3gMk9jY0=; b=NSFUXLIzxsTzG539xksZu9OhX2Z0UxqPZ3PPN/tAOMKCTw4zHk7KQkXYKC4PESwP39 IO9NhWQda4+IzZieT/3H4ZVj5LwJkTWdemBLUDfVjKIErBIREu7rg22Ncht46SCDpIZO YvwZLetomUOHD6d41deMa3K1UjNT/Bx0tAGBlhEhBOzwn7XTpDPVG/Sum0vsjIHlJLKr YQD+E4LMM0+dSiO2U2Gu0EvO/JHIkd+MJ4D4Szi86VWgfT4wW8DDm0ctGaec5BK4hAjT 1wixpS075edw440EiYudGSS7ju3M5ykFxSMG708YulfJ4ldItYHv46Qx2n5cVo7th0Fe pFCw== X-Gm-Message-State: APjAAAXudOIWdn5o3Dzn3uTlQSc0O3/IZkgYIZUnb/5vG9lJZ3kwpEyZ NVru7DA41NJ9Kv28rR8nIywZgAxzSjBmLGD70nqCCb9mYalAiQ== X-Google-Smtp-Source: APXvYqxq23c54bfWmKNY1x+nomIQ+g5QNYTgWlzistI8eYNkLPIZUUyXsKRJxxJKc3UFtzsP6ZCBTOTecnJWtTezXj0= X-Received: by 2002:a65:5542:: with SMTP id t2mr4116778pgr.74.1572031031301; Fri, 25 Oct 2019 12:17:11 -0700 (PDT) MIME-Version: 1.0 References: <20191025190047.38130-1-stuart.w.hayes@gmail.com> <20191025190047.38130-3-stuart.w.hayes@gmail.com> In-Reply-To: <20191025190047.38130-3-stuart.w.hayes@gmail.com> From: Andy Shevchenko Date: Fri, 25 Oct 2019 22:16:59 +0300 Message-ID: Subject: Re: [PATCH v4 2/3] PCI: pciehp: Wait for PDS if in-band presence is disabled To: Stuart Hayes Cc: Bjorn Helgaas , Austin Bolen , Keith Busch , Alexandru Gagniuc , "Rafael J . Wysocki" , Mika Westerberg , "Gustavo A . R . Silva" , Sinan Kaya , Oza Pawandeep , linux-pci@vger.kernel.org, Linux Kernel Mailing List , Lukas Wunner Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 25, 2019 at 10:01 PM Stuart Hayes wrote: > > From: Alexandru Gagniuc > > When inband presence is disabled, PDS may come up at any time, or not > at all. PDS being low may indicate that the card is still mating, and > we could expect contact bounce to bring down the link as well. > > It is reasonable to assume that most cards will mate in a hotplug slot > in about a second. Thus, when we know PDS only reflects out-of-band > presence, it's worthwhile to wait the extra second or so to make sure > the card is properly mated before loading the driver, and to prevent > the hotplug code from disabling a device if the presence detect change > goes active after the device is enabled. > FWIW, Reviewed-by: Andy Shevchenko > Signed-off-by: Alexandru Gagniuc > Signed-off-by: Stuart Hayes > --- > v2: > replace while(true) loop with do...while > v3 > remove unused variable declaration (pds) > modify text of warning message > v4 > remove "!!" boolean conversion from "if" condition for readability > > drivers/pci/hotplug/pciehp_hpc.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c > index dc109d521f30..02d95ab27a12 100644 > --- a/drivers/pci/hotplug/pciehp_hpc.c > +++ b/drivers/pci/hotplug/pciehp_hpc.c > @@ -242,6 +242,22 @@ static bool pci_bus_check_dev(struct pci_bus *bus, int devfn) > return found; > } > > +static void pcie_wait_for_presence(struct pci_dev *pdev) > +{ > + int timeout = 1250; > + u16 slot_status; > + > + do { > + pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status); > + if (slot_status & PCI_EXP_SLTSTA_PDS) > + return; > + msleep(10); > + timeout -= 10; > + } while (timeout > 0); > + > + pci_info(pdev, "Timeout waiting for Presence Detect state to be set\n"); > +} > + > int pciehp_check_link_status(struct controller *ctrl) > { > struct pci_dev *pdev = ctrl_dev(ctrl); > @@ -251,6 +267,9 @@ int pciehp_check_link_status(struct controller *ctrl) > if (!pcie_wait_for_link(pdev, true)) > return -1; > > + if (ctrl->inband_presence_disabled) > + pcie_wait_for_presence(pdev); > + > found = pci_bus_check_dev(ctrl->pcie->port->subordinate, > PCI_DEVFN(0, 0)); > > -- > 2.18.1 > -- With Best Regards, Andy Shevchenko