linux-kernel - Re: [PATCH v3 0/4] DT schema changes for HiKey970 PCIe hardware to work

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Date:   Fri, 6 Aug 2021 10:23:35 -0600
From:   Rob Herring <robh@...nel.org>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     Linuxarm <linuxarm@...wei.com>, mauro.chehab@...wei.com,
        Binghui Wang <wangbinghui@...ilicon.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Xiaowei Song <songxiaowei@...ilicon.com>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        PCI <linux-pci@...r.kernel.org>, linux-phy@...ts.infradead.org
Subject: Re: [PATCH v3 0/4] DT schema changes for HiKey970 PCIe hardware to work

On Thu, Aug 5, 2021 at 1:58 AM Mauro Carvalho Chehab
<mchehab+huawei@...nel.org> wrote:
>
> Em Thu, 5 Aug 2021 09:46:12 +0200
> Mauro Carvalho Chehab <mchehab+huawei@...nel.org> escreveu:
>
> > Em Wed, 4 Aug 2021 10:28:53 -0600
> > Rob Herring <robh@...nel.org> escreveu:
> >
> > > On Wed, Aug 04, 2021 at 08:50:45AM +0200, Mauro Carvalho Chehab wrote:
> > > > Em Tue, 3 Aug 2021 16:11:42 -0600
> > > > Rob Herring <robh+dt@...nel.org> escreveu:
> > > >
> > > > > On Mon, Aug 2, 2021 at 10:39 PM Mauro Carvalho Chehab
> > > > > <mchehab+huawei@...nel.org> wrote:
> > > > > >
> > > > > > Hi Rob,
> > > > > >
> > > > > > That's the third version of the DT bindings for Kirin 970 PCIE and its
> > > > > > corresponding PHY.
> > > > > >
> > > > > > It is identical to v2, except by:
> > > > > >         -          pcie@7,0 { // Lane 7: Ethernet
> > > > > >         +          pcie@7,0 { // Lane 6: Ethernet
> > > > >
> > > > > Can you check whether you have DT node links in sysfs for the PCI
> > > > > devices? If you don't, then something is wrong still in the topology
> > > > > or the PCI core is failing to set the DT node pointer in struct
> > > > > device. Though you don't rely on that currently, we want the topology
> > > > > to match. It's possible this never worked on arm/arm64 as mainly
> > > > > powerpc relied on this.
> > > > >
> > > > > I'd like some way to validate the DT matches the PCI topology. We
> > > > > could have a tool that generates the DT structure based on the PCI
> > > > > topology.
> > > >
> > > > The of_node node link is on those places:
> > > >
> > > >   $ find /sys/devices/platform/soc/f4000000.pcie/ -name of_node
> > > >   /sys/devices/platform/soc/f4000000.pcie/of_node
> > > >   /sys/devices/platform/soc/f4000000.pcie/pci0000:00/0000:00:00.0/of_node
> > > >   /sys/devices/platform/soc/f4000000.pcie/pci0000:00/0000:00:00.0/pci_bus/0000:01/of_node
> > > >   /sys/devices/platform/soc/f4000000.pcie/pci0000:00/pci_bus/0000:00/of_node
> > >
> > > Looks like we're missing some...
> > >
> > > It's not immediately obvious to me what's wrong here. Only the root
> > > bus is getting it's DT node set. The relevant code is pci_scan_device(),
> > > pci_set_of_node() and pci_set_bus_of_node(). Give me a few days to try
> > > to reproduce and debug it.
> >
> > I added a printk on both pci_set_*of_node() functions:
> >
> >       [    4.872991]  (null): pci_set_bus_of_node: of_node: /soc/pcie@...00000
> >       [    4.913806]  (null): pci_set_of_node: of_node: /soc/pcie@...00000
> >       [    4.978102] pci_bus 0000:01: pci_set_bus_of_node: of_node: /soc/pcie@...00000/pcie@0,0
> >       [    4.990622]  (null): pci_set_of_node: of_node: /soc/pcie@...00000/pcie@0,0
> >       [    5.052383] pci_bus 0000:02: pci_set_bus_of_node: of_node: (null)
> >       [    5.059263]  (null): pci_set_of_node: of_node: (null)
> >       [    5.085552]  (null): pci_set_of_node: of_node: (null)
> >       [    5.112073]  (null): pci_set_of_node: of_node: (null)
> >       [    5.138320]  (null): pci_set_of_node: of_node: (null)
> >       [    5.164673]  (null): pci_set_of_node: of_node: (null)
> >       [    5.233759] pci_bus 0000:03: pci_set_bus_of_node: of_node: (null)
> >       [    5.240539]  (null): pci_set_of_node: of_node: (null)
> >       [    5.310545] pci_bus 0000:04: pci_set_bus_of_node: of_node: (null)
> >       [    5.324719] pci_bus 0000:05: pci_set_bus_of_node: of_node: (null)
> >       [    5.338914] pci_bus 0000:06: pci_set_bus_of_node: of_node: (null)
> >       [    5.345516]  (null): pci_set_of_node: of_node: (null)
> >       [    5.415795] pci_bus 0000:07: pci_set_bus_of_node: of_node: (null)
>
> The enclosed patch makes the above a clearer:
>
>         [    4.800975]  (null): pci_set_bus_of_node: of_node: /soc/pcie@...00000
>         [    4.855983] pci 0000:00:00.0: pci_set_of_node: of_node: /soc/pcie@...00000
>         [    4.879169] pci_bus 0000:01: pci_set_bus_of_node: of_node: /soc/pcie@...00000/pcie@0,0
>         [    4.900602] pci 0000:01:00.0: pci_set_of_node: of_node: /soc/pcie@...00000/pcie@0,0
>         [    4.953086] pci_bus 0000:02: pci_set_bus_of_node: of_node: (null)

I believe the issue is we need another bridge node in the DT
hierarchy. What we have is:

Bus 0 is node /soc/pcie@...00000
Bus 1 is device 0 on bus 0 is node /soc/pcie@...00000/pcie@0,0
Bus 2 is device 0 on bus 1 in node ... whoops, there's no device 0
under /soc/pcie@...00000/pcie@0,0

So we need the hierarchy to be: /soc/pcie@...00000/pcie@...cie@...cie@{1,5,7}

Rob