linux-kernel - Re: [PATCH v4 4/5] dm: pci: Assign controller device node to root bridge

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Date:   Thu, 25 Jun 2020 19:12:02 -0600
From:   Simon Glass <sjg@...omium.org>
To:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Cc:     Matthias Brugger <mbrugger@...e.com>,
        U-Boot Mailing List <u-boot@...ts.denx.de>,
        Bin Meng <bmeng.cn@...il.com>, Marek Vasut <marex@...x.de>,
        lk <linux-kernel@...r.kernel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Mark Kettenis <mark.kettenis@...all.nl>
Subject: Re: [PATCH v4 4/5] dm: pci: Assign controller device node to root bridge

Hi Nicolas,

On Wed, 17 Jun 2020 at 13:15, Nicolas Saenz Julienne
<nsaenzjulienne@...e.de> wrote:
>
> On Tue, 2020-06-16 at 17:31 -0600, Simon Glass wrote:
> > Hi Nicolas,
> >
> > On Tue, 16 Jun 2020 at 08:09, Nicolas Saenz Julienne
> > <nsaenzjulienne@...e.de> wrote:
> > > On Tue, 2020-06-16 at 07:43 -0600, Simon Glass wrote:
> > > > Hi Nicolas,
> > > >
> > > > On Fri, 12 Jun 2020 at 10:47, Nicolas Saenz Julienne
> > > > <nsaenzjulienne@...e.de> wrote:
> > > > > There is no distinction in DT between the PCI controller device and the
> > > > > root bridge, whereas such distinction exists from dm's perspective. Make
> > > > > sure the root bridge ofnode is assigned to the controller's platform
> > > > > device node.
> > > > >
> > > > > This permits setups like this to work correctly:
> > > > >
> > > > >         pcie {
> > > > >                 compatible = "...";
> > > > >                 ...
> > > > >                 dev {
> > > > >                         reg = <0 0 0 0 0>;
> > > > >                         ...
> > > > >                 };
> > > > >         };
> > > > >
> > > > > Without this the dev node is assigned to the root bridge and the
> > > > > actual device search starts one level lower than expected.
> > > > >
> > > > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> > > > > ---
> > > > >  drivers/pci/pci-uclass.c | 15 ++++++++++++++-
> > > > >  1 file changed, 14 insertions(+), 1 deletion(-)
> > > >
> > > > Can you update the tests to handle this case please?
> > >
> > > I'd be glad to, but I'm not familiar with the test FW in u-booy, coud give
> > > me
> > > some pointers on where/how to test this?
> > >
> >
> > Yes it is at test/dm/pci.c and the device tree is test.dts
> >
> > 'make qcheck' to run all tests. To run one test, build for sandbox and
> > then something like
> >
> > u-boot -T -c "ut dm pci_swapcase"
> >
> > for example.
> >
> > You can perhaps use an existing PCI controller in test.dts but feel
> > free to add one more if you need it for your test. Make sure that you
> > don't break other tests.
>
> Thanks for the info.
>
> Actually adding the tests made me doubleguess myself, and now I'm pretty sure
> that what I shoudl've done in DT is the following:
>
>         &pcie0 {
>                pci@0 {
>                        #address-cells = <3>;
>                        #size-cells = <2>;
>                        ranges;
>
>                        reg = <0 0 0 0 0>;
>
>                        usb@1,0 {
>                                reg = <0x10000 0 0 0 0>;
>                                resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
>                        };
>                };
>         };
>
>
> (with "lspci -tv": [0000:00]---00.0-[01]----00.0  VIA Technologies, Inc. VL805 USB 3.0 Host Controller)
>
> With this the patch above isn't needed, which is great.
>
> I'll send this to upstream Linux just to get a confirmation this is correct,
> although if you have any comments it'll be appreciated.

Yes it looks OK to me. U-Boot allows PCI and USB devices to be
represented in the device tree.

Regards,
Simon