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Date:   Thu, 8 Sep 2022 12:45:16 -0700
From:   Dan Williams <dan.j.williams@intel.com>
To:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>
CC:     Robert Richter <rrichter@amd.com>,
        Alison Schofield <alison.schofield@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        "Ira Weiny" <ira.weiny@intel.com>,
        Ben Widawsky <bwidawsk@kernel.org>,
        "Bjorn Helgaas" <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
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        Len Brown <lenb@kernel.org>,
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        ACPI Devel Maling List <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH 06/15] PCI/ACPI: Link host bridge to its ACPI fw node
Message-ID: <631a464c166cc_166f294d5@dwillia2-xfh.jf.intel.com.notmuch>
References: <20220831081603.3415-1-rrichter@amd.com>
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Rafael J. Wysocki wrote:
> On Thu, Sep 8, 2022 at 8:05 AM Dan Williams <dan.j.williams@intel.com> wrote:
> >
> > Robert Richter wrote:
> > > A lookup of a host bridge's corresponding acpi device (struct
> > > acpi_device) is not possible, for example:
> > >
> > >       adev = ACPI_COMPANION(&host_bridge->dev);
> > >
> > > This could be useful to find a host bridge's fwnode handle and to
> > > determine and call additional host bridge ACPI parameters and methods
> > > such as HID/CID or _UID.
> >
> > When is this explicitly needed. "Could be useful" is interesting, but it
> > needs to have a practical need.
> 
> It is needed and it is present on x86 AFAICS (see my last reply in this thread).
> 
> This seems to be addressing an ARM64-specific issue.
> 

Ah, ok, thanks for pointing that out.