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From: Bartosz Golaszewski <brgl@bgdev.pl>
Date: Wed, 10 Jan 2024 17:26:52 +0100
Message-ID: <CAMRc=MdBSAb_kEO2r7r-vwLuRAEv7pMODOMtZoCCRAd=zsQb_w@mail.gmail.com>
Subject: Re: [RFC 3/9] PCI/portdrv: create platform devices for child OF nodes
To: Lukas Wunner <lukas@wunner.de>
Cc: Kalle Valo <kvalo@kernel.org>, "David S . Miller" <davem@davemloft.net>, 
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>, 
	Rob Herring <robh+dt@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Bjorn Andersson <andersson@kernel.org>, Konrad Dybcio <konrad.dybcio@linaro.org>, 
	Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, 
	Bjorn Helgaas <bhelgaas@google.com>, Heiko Stuebner <heiko@sntech.de>, 
	Jernej Skrabec <jernej.skrabec@gmail.com>, Chris Morgan <macromorgan@hotmail.com>, 
	Linus Walleij <linus.walleij@linaro.org>, Geert Uytterhoeven <geert+renesas@glider.be>, 
	Arnd Bergmann <arnd@arndb.de>, Neil Armstrong <neil.armstrong@linaro.org>, 
	=?UTF-8?B?TsOtY29sYXMgRiAuIFIgLiBBIC4gUHJhZG8=?= <nfraprado@collabora.com>, 
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	Robert Richter <rrichter@amd.com>, Dan Williams <dan.j.williams@intel.com>, 
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	Huacai Chen <chenhuacai@kernel.org>, Alex Elder <elder@linaro.org>, 
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	linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, 
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	Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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On Wed, Jan 10, 2024 at 2:28=E2=80=AFPM Lukas Wunner <lukas@wunner.de> wrot=
e:
>
> On Wed, Jan 10, 2024 at 01:55:18PM +0100, Bartosz Golaszewski wrote:
> > On Tue, Jan 9, 2024 at 3:43???PM Lukas Wunner <lukas@wunner.de> wrote:
> > > On Thu, Jan 04, 2024 at 02:01:17PM +0100, Bartosz Golaszewski wrote:
> > > > In order to introduce PCIe power-sequencing, we need to create plat=
form
> > > > devices for child nodes of the port driver node. They will get matc=
hed
> > > > against the pwrseq drivers (if one exists) and then the actuak PCIe
> > > > device will reuse the node once it's detected on the bus.
> > > [...]
> > > > --- a/drivers/pci/pcie/portdrv.c
> > > > +++ b/drivers/pci/pcie/portdrv.c
> > > > @@ -715,7 +716,7 @@ static int pcie_portdrv_probe(struct pci_dev *d=
ev,
> > > >               pm_runtime_allow(&dev->dev);
> > > >       }
> > > >
> > > > -     return 0;
> > > > +     return devm_of_platform_populate(&dev->dev);
> > > >  }
> > >
> > > I think this belongs in of_pci_make_dev_node(), portdrv seems totally
> > > the wrong place.  Note that you're currently calling this for RCECs
> > > (Root Complex Event Collectors) as well, which is likely not what
> > > you want.
> > >
> >
> > of_pci_make_dev_node() is only called when the relevant PCI device is
> > instantiated which doesn't happen until it's powered-up and scanned -
> > precisely the problem I'm trying to address.
>
> No, of_pci_make_dev_node() is called *before* device_attach(),
> i.e. before portdrv has even probed.  So it seems this should
> work perfectly well for your use case.
>

Seems like the following must be true but isn't in my case (from
pci_bus_add_device()):

    if (pci_is_bridge(dev))
        of_pci_make_dev_node(dev);

Shouldn't it evaluate to true for ports?

Bartosz

[snip]