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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 9AC86C282C4 for ; Tue, 12 Feb 2019 08:55:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F0632080A for ; Tue, 12 Feb 2019 08:55:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728461AbfBLIzG (ORCPT ); Tue, 12 Feb 2019 03:55:06 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:38379 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728086AbfBLIzG (ORCPT ); Tue, 12 Feb 2019 03:55:06 -0500 Received: from kresse.hi.pengutronix.de ([2001:67c:670:100:1d::2a]) by metis.ext.pengutronix.de with esmtp (Exim 4.89) (envelope-from ) id 1gtTqC-0004fM-KI; Tue, 12 Feb 2019 09:54:56 +0100 Message-ID: <1549961694.2546.18.camel@pengutronix.de> Subject: Re: [PATCH 2/2] PCI: imx6: limit DBI register length From: Lucas Stach To: Bjorn Helgaas , Stefan Agner Cc: lorenzo.pieralisi@arm.com, jingoohan1@gmail.com, gustavo.pimentel@synopsys.com, tpiepho@impinj.com, leonard.crestez@nxp.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 12 Feb 2019 09:54:54 +0100 In-Reply-To: <20190211213900.GA247873@google.com> References: <14fafdf52d19feb9c926c312f4e3ba7ff8a4bad9.1549446867.git.stefan@agner.ch> <119211b4f2e9ada55b86041d009656e49c2b5281.1549446867.git.stefan@agner.ch> <20190211213900.GA247873@google.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::2a X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-pci@vger.kernel.org Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi Bjorn, Am Montag, den 11.02.2019, 15:39 -0600 schrieb Bjorn Helgaas: > On Wed, Feb 06, 2019 at 10:57:32AM +0100, Stefan Agner wrote: > > Define the length of the DBI registers. This makes sure that > > the kernel does not access registers beyond that point, avoiding > > the following abort on a i.MX 6Quad: > >   # cat /sys/devices/soc0/soc/1ffc000.pcie/pci0000\:00/0000\:00\:00.0/config > >   [  100.021433] Unhandled fault: imprecise external abort (0x1406) at 0xb6ea7000 > >   ... > >   [  100.056423] PC is at dw_pcie_read+0x50/0x84 > >   [  100.060790] LR is at dw_pcie_rd_own_conf+0x44/0x48 > >   ... > > I assume this problem happens when using the pci_read_config() path or > something similar? > > Could this be solved using pci_dev.cfg_size instead of building a new > dwc-specific mechanism?  There are some quirks that set dev->cfg_size > to keep from reading past certain points in config space, e.g., > quirk_citrine(), quirk_nfp6000(). > > I'm not necessarily opposed to doing it in dwc, but maybe there's some > advantage in reducing the number of ways of doing the same thing. This actually started out as a quirk changing the cfg size. But the valid config space size seems to be different between root ports that share the same (broken) device ID (Synopsys abcd), so I doubt that this would be easier and/or any cleaner to implement as a quirk. Regards, Lucas > > Signed-off-by: Stefan Agner > > > > Reviewed-by: Lucas Stach > > --- > > Changes in v3: > > - Rebase on pci/dwc > > Changes in v4: > > - Rebase on pci/dwc > > Changes in v5: > > - Rebased ontop of pci/dwc > > - Use DBI length of 0x200 > > > >  drivers/pci/controller/dwc/pci-imx6.c | 4 ++++ > >  1 file changed, 4 insertions(+) > > > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c > > index c1d434ba3642..1ef7be1232f3 100644 > > --- a/drivers/pci/controller/dwc/pci-imx6.c > > +++ b/drivers/pci/controller/dwc/pci-imx6.c > > @@ -55,6 +55,7 @@ enum imx6_pcie_variants { > >  struct imx6_pcie_drvdata { > > > >   enum imx6_pcie_variants variant; > > > >   u32 flags; > > > > + int dbi_length; > >  }; > >   > >  struct imx6_pcie { > > @@ -1087,6 +1088,8 @@ static int imx6_pcie_probe(struct platform_device *pdev) > > > >   break; > > > >   } > >   > > > > + pci->dbi_length = imx6_pcie->drvdata->dbi_length; > > + > > > >   /* Grab turnoff reset */ > > > >   imx6_pcie->turnoff_reset = devm_reset_control_get_optional_exclusive(dev, "turnoff"); > > > >   if (IS_ERR(imx6_pcie->turnoff_reset)) { > > @@ -1170,6 +1173,7 @@ static const struct imx6_pcie_drvdata drvdata[] = { > > > >   .variant = IMX6Q, > > > >   .flags = IMX6_PCIE_FLAG_IMX6_PHY | > > > >    IMX6_PCIE_FLAG_IMX6_SPEED_CHANGE, > > > > + .dbi_length = 0x200, > > > >   }, > > > >   [IMX6SX] = { > > > >   .variant = IMX6SX, > > --  > > 2.20.1 > >