netdev - Re: [PATCH pci] PCI: don't skip probing entire device if first fn OF node has status = "disabled"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230604085500.ioaos3ydehvqq24i@skbuf>
Date: Sun, 4 Jun 2023 11:55:00 +0300
From: Vladimir Oltean <vladimir.oltean@....com>
To: Jianmin Lv <lvjianmin@...ngson.cn>
Cc: Liu Peibao <liupeibao@...ngson.cn>, Bjorn Helgaas <helgaas@...nel.org>,
	linux-pci@...r.kernel.org, netdev@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>, Rob Herring <robh@...nel.org>,
	Claudiu Manoil <claudiu.manoil@....com>,
	Michael Walle <michael@...le.cc>, linux-kernel@...r.kernel.org,
	Binbin Zhou <zhoubinbin@...ngson.cn>,
	Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH pci] PCI: don't skip probing entire device if first fn OF
 node has status = "disabled"

On Sat, Jun 03, 2023 at 10:35:50AM +0800, Jianmin Lv wrote:
> > How about 3. handle of_device_is_available() in the probe function of
> > the "loongson, pci-gmac" driver? Would that not work?
> > 
> This way does work only for the specified device. There are other devices,
> such as HDA, I2S, etc, which have shared pins. Then we have to add
> of_device_is_available() checking to those drivers one by one. And we are
> not sure if there are other devices in new generation chips in future. So
> I'm afraid that the way you mentioned is not suitable for us.

Got it, so you have more on-chip PCIe devices than the ones listed in
loongson64-2k1000.dtsi, and you don't want to describe them in the
device tree just to put status = "disabled" for those devices/functions
that you don't want Linux to use - although you could, and it wouldn't
be that hard or have unintended side effects.

Though you need to admit, in case you had an on-chip multi-function PCIe
device like the NXP ENETC, and you wanted Linux to not use function 0,
the strategy you're suggesting here that is acceptable for Loongson
would not have worked.

I believe we need a bit of coordination from PCIe and device tree
maintainers, to suggest what would be the encouraged best practices and
ways to solve this regression for the ENETC.