Re: [PATCH V13 0/5] Generate device tree node for pci devices

Herve Codina
2023-09-21T18:12:25Z

On Thu, 21 Sep 2023 07:20:46 -0500
Rob Herring <robh@kernel.org> wrote:

> On Mon, Sep 18, 2023 at 2:17 AM Andy Shevchenko
> <andriy.shevchenko@intel.com> wrote:
> >
> > On Fri, Sep 15, 2023 at 07:30:08PM +0200, Herve Codina wrote:
> > > On Wed, 13 Sep 2023 14:17:30 +0300
> > > Andy Shevchenko <andriy.shevchenko@intel.com> wrote:
> > > > On Tue, Sep 12, 2023 at 02:12:04PM -0500, Rob Herring wrote:
> > > > > On Mon, Sep 11, 2023 at 3:37 PM Andy Shevchenko
> > > > > <andriy.shevchenko@intel.com> wrote:
> > > > > > On Tue, Aug 15, 2023 at 10:19:55AM -0700, Lizhi Hou wrote:
> >
> > ...
> >
> > > > > > Can you point out to the ACPI excerpt(s) of the description of anything related
> > > > > > to the device(s) in question?
> > > > >
> > > > > I don't understand what you are asking for.
> > > >
> > > > Through the email thread it was mentioned that this series was tested on the
> > > > ACPI enabled platform, Jonathan (IIRC) asked why do we need to have a shadow
> > > > DT for the something that ACPI already describes. That's why I'm trying to
> > > > understand if it's the case. and if so, how can we improve the approach.
> > >
> > > Patches from Frank Rowand series [1] are needed to create an of_root_node if a DT
> > > was not provided by the firmware, bootloader, etc that run the kernel.
> > >
> > > [1]: https://lore.kernel.org/lkml/20220624034327.2542112-1-frowand.list@gmail.com/
> > >
> > > Current Lizhi's series creates nodes from the PCI host node during the PCI
> > > enumeration. It creates PCI-PCI bridge and PCI device nodes.
> > >
> > > I use these series on an ACPI system.
> > >
> > > I need one more missing component: the node related to the PCI host bridge
> > > This was the purpose of Clement's work. This work was not sent upstream yet and I
> > > am working on it in order to have a full tree from the of_root to the PCI device
> > > ie:
> > > of_root <-- Frank Rowand series
> > > + of_host_pci_bridge <-- Clement's work
> > > + pci_bridge <-- Current Lizhi series
> > > + pci_bridge <-- Current Lizhi series
> > > ...
> > > + pci_dev <-- Current Lizhi series
> > >
> > > Hope that this status helped.
> >
> > Thanks for the explanation! I suppose it's better to have three series combined
> > into one and being sent with a better cover letter to explain all this.
>
> You can go back (years now) and see that. I asked for this to be split
> up into manageable chunks and not solve multiple problems at once. No
> point in trying to do DT on top of ACPI if DT on top of DT doesn't
> work first.

I agree.

Hervé

>
> Rob

--
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering