linux-kernel - RE: [PATCH 2/2] PCI: imx6: limit DBI register length

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Message-ID: <VI1PR04MB553386A3F452E13BFCF79688EED90@VI1PR04MB5533.eurprd04.prod.outlook.com>
Date:   Tue, 20 Nov 2018 13:03:38 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     Stefan Agner <stefan@...er.ch>, Richard Zhu <hongxing.zhu@....com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jingoohan1@...il.com" <jingoohan1@...il.com>,
        "gustavo.pimentel@...opsys.com" <gustavo.pimentel@...opsys.com>,
        "tpiepho@...inj.com" <tpiepho@...inj.com>,
        "andrew.smirnov@...il.com" <andrew.smirnov@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>
Subject: RE: [PATCH 2/2] PCI: imx6: limit DBI register length

From: Stefan Agner <stefan@...er.ch>
> On 20.11.2018 11:22, Leonard Crestez wrote:
> > On Mon, 2018-11-19 at 10:41 +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
> >>   ...
> >>
> >> Signed-off-by: Stefan Agner <stefan@...er.ch>
> >>
> >> diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> >
> >> +struct imx6_pcie_drvdata {
> >> +	enum imx6_pcie_variants variant;
> >> +	int			dbi_length;
> >> +};
> >
> > Turning imx6_pcie drvdata into a struct is very nice, maybe in the
> > future some of the long case statements in this driver could be split
> > into per-soc functions called via drvdata.
> 
> Yeah I thought that too. At a quick glance I did not saw an obvious
> contender. Should certainly help for similar cases in the future.

Yes, there are other cases in which it would be useful.

But I think it makes more sense to split introducing drvdata to a separate patch.
It's nice to separate functional and code cleanup changes.

For example maybe dbi_length causes issues and has to be reverted?

--
Regards,
Leonard