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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=ham 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 0B7CEC433DF for ; Tue, 30 Jun 2020 13:54:56 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C970C20774 for ; Tue, 30 Jun 2020 13:54:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="TdhevkAd"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="kCZGDQTU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C970C20774 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Message-ID:Subject:To:From: Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References:List-Owner; bh=ZwCiQzEqxNKo066MV+NvDGeJ/qMcZytMElz0MP4hPUo=; b=TdhevkAdj/pf4GKkP1bCN0ObT 9oZl8OmV5TeHmOT1FcBAKPBwdBvU4O96CdzZa9H9tiSG8CIbsw/7DKkql8wWN4kJapHXovlNosRwq dHyIoTSUonJ0ADLCOuW9AcDCepGYcURv1aAtpVK1MMOyfHxvlPo5s7PBDZbGaorVNMBrjwxN20SrX Hl9qt4gTpuIB9wXngv76zTiOe4ExlqSLAvfHqR06o/0mmsrho9PG4s43Gd0PdZRrr+nFXrUJ/Mr53 SrBFoIFO/edsrn5ry65d2EAUQro6YDEL+UWCzpRt3C/d+c3eHOaNYrKS1CNg74YH23fdi12qEUd/s MLa9ZQctQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jqGhQ-00027B-H0; Tue, 30 Jun 2020 13:53:24 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jqGfa-0001El-C9 for linux-arm-kernel@lists.infradead.org; Tue, 30 Jun 2020 13:51:31 +0000 Received: from localhost (mobile-166-175-191-139.mycingular.net [166.175.191.139]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 047A8206BE; Tue, 30 Jun 2020 13:51:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593525089; bh=DT35ELVgMqJzlhLA7qu4G6VgRNYAREppcPFMWUWIO0M=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=kCZGDQTUUI2rEIYfln/G2FtlWnJuHoW3ylN6MmFEOreoxaDbPeX9ZkAIFhOOAY0lU HE/T9DodsxPnfGzgRSOhiH+J2ZyzmkjUFPe1RznrUtTigIsLS0RyD4I6QbQ1AEkbPR 4HMWBIN5v2/s/AG9OekjEZo/C1oFsae9WVFnB69k= Date: Tue, 30 Jun 2020 08:51:27 -0500 From: Bjorn Helgaas To: Pali =?iso-8859-1?Q?Roh=E1r?= Subject: Re: [PATCH] PCI: aardvark: Don't touch PCIe registers if no card connected Message-ID: <20200630135127.GA3414186@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200528163809.54f5ldvphrjg3zg3@pali> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tomasz Maciej Nowak , Lorenzo Pieralisi , linux-pci@vger.kernel.org, Xogium , linux-kernel@vger.kernel.org, Marek =?iso-8859-1?Q?Beh=FAn?= , Remi Pommarel , Thomas Petazzoni , Bjorn Helgaas , linux-arm-kernel@lists.infradead.org, Andrew Murray Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, May 28, 2020 at 06:38:09PM +0200, Pali Roh=E1r wrote: > On Thursday 28 May 2020 11:26:04 Bjorn Helgaas wrote: > > On Thu, May 28, 2020 at 04:31:41PM +0200, Pali Roh=E1r wrote: > > > When there is no PCIe card connected and advk_pcie_rd_conf() or > > > advk_pcie_wr_conf() is called for PCI bus which doesn't belong to emu= lated > > > root bridge, the aardvark driver throws the following error message: > > > = > > > advk-pcie d0070000.pcie: config read/write timed out > > > = > > > Obviously accessing PCIe registers of disconnected card is not possib= le. > > > = > > > Extend check in advk_pcie_valid_device() function for validating > > > availability of PCIe bus. If PCIe link is down, then the device is ma= rked > > > as Not Found and the driver does not try to access these registers. > > > = > > > Signed-off-by: Pali Roh=E1r > > > --- > > > drivers/pci/controller/pci-aardvark.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > = > > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/cont= roller/pci-aardvark.c > > > index 90ff291c24f0..53a4cfd7d377 100644 > > > --- a/drivers/pci/controller/pci-aardvark.c > > > +++ b/drivers/pci/controller/pci-aardvark.c > > > @@ -644,6 +644,9 @@ static bool advk_pcie_valid_device(struct advk_pc= ie *pcie, struct pci_bus *bus, > > > if ((bus->number =3D=3D pcie->root_bus_nr) && PCI_SLOT(devfn) !=3D = 0) > > > return false; > > > = > > > + if (bus->number !=3D pcie->root_bus_nr && !advk_pcie_link_up(pcie)) > > > + return false; > > = > > I don't think this is the right fix. This makes it racy because the > > link may go down after we call advk_pcie_valid_device() but before we > > perform the config read. > = > Yes, it is racy, but I do not think it cause problems. Trying to read > PCIe registers when device is not connected cause just those timeouts, > printing error message and increased delay in advk_pcie_wait_pio() due > to polling loop. This patch reduce unnecessary access to PCIe registers > when advk_pcie_wait_pio() polling just fail. What happens when the device is removed after advk_pcie_link_up() returns true, but before we actually do the config access? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel