netdev - Re: [PATCH 4/9] PCI: create platform devices for child OF nodes of the port node

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Date: Thu, 18 Jan 2024 14:11:30 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Dan Williams <dan.j.williams@...el.com>
Cc: Kalle Valo <kvalo@...nel.org>, "David S . Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Heiko Stuebner <heiko@...ech.de>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Chris Morgan <macromorgan@...mail.com>, 
	Linus Walleij <linus.walleij@...aro.org>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Arnd Bergmann <arnd@...db.de>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Nícolas F . R . A . Prado <nfraprado@...labora.com>, 
	Marek Szyprowski <m.szyprowski@...sung.com>, Peng Fan <peng.fan@....com>, 
	Robert Richter <rrichter@....com>, Jonathan Cameron <Jonathan.Cameron@...wei.com>, 
	Terry Bowman <terry.bowman@....com>, Lukas Wunner <lukas@...ner.de>, 
	Huacai Chen <chenhuacai@...nel.org>, Alex Elder <elder@...aro.org>, 
	Srini Kandagatla <srinivas.kandagatla@...aro.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Abel Vesa <abel.vesa@...aro.org>, 
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-pci@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 4/9] PCI: create platform devices for child OF nodes of
 the port node

On Wed, Jan 17, 2024 at 5:22 PM Dan Williams <dan.j.williams@...el.com> wrote:
>
> Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > In order to introduce PCI power-sequencing, we need to create platform
> > devices for child nodes of the port node. They will get matched against
> > the pwrseq drivers (if one exists) and then the actual PCI device will
> > reuse the node once it's detected on the bus.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> [..]
> > diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> > index d749ea8250d6..77be0630b7b3 100644
> > --- a/drivers/pci/remove.c
> > +++ b/drivers/pci/remove.c
> > @@ -1,6 +1,7 @@
> >  // SPDX-License-Identifier: GPL-2.0
> >  #include <linux/pci.h>
> >  #include <linux/module.h>
> > +#include <linux/of_platform.h>
> >  #include "pci.h"
> >
> >  static void pci_free_resources(struct pci_dev *dev)
> > @@ -18,11 +19,11 @@ static void pci_stop_dev(struct pci_dev *dev)
> >       pci_pme_active(dev, false);
> >
> >       if (pci_dev_is_added(dev)) {
> > -
> >               device_release_driver(&dev->dev);
> >               pci_proc_detach_device(dev);
> >               pci_remove_sysfs_dev_files(dev);
> >               of_pci_remove_node(dev);
> > +             of_platform_depopulate(&dev->dev);
> >
> >               pci_dev_assign_added(dev, false);
>
> Why is pci_stop_dev() not in strict reverse order of
> pci_bus_add_device()? I see that pci_dev_assign_added() was already not
> in reverse "add" order before your change, but I otherwise would have
> expected of_platform_depopulate() before of_pci_remove_node() (assumed
> paired with of_pci_make_dev_node()).

The naming here is confusing but the two have nothing in common. One
is used by CONFIG_PCI_DYNAMIC_OF_NODES to *create* new DT nodes for
detected PCI devices. The one I'm adding, creates power sequencing
*devices* (no nodes) for *existing* DT nodes.

So the order is not really relevant here but I can change in v2.

Bartosz