linux-kernel - Re: [PATCH v4 2/6] dt-bindings: PCI: Add bindings for Brcmstb endpoint device voltage regulators

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: <20210408162016.GA1556444@robh.at.kernel.org>
Date:   Thu, 8 Apr 2021 11:20:16 -0500
From:   Rob Herring <robh@...nel.org>
To:     Jim Quinlan <jim2101024@...il.com>
Cc:     Mark Brown <broonie@...nel.org>,
        linux-pci <linux-pci@...r.kernel.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        Jim Quinlan <james.quinlan@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/6] dt-bindings: PCI: Add bindings for Brcmstb
 endpoint device voltage regulators

On Tue, Apr 06, 2021 at 02:25:49PM -0400, Jim Quinlan wrote:
> On Tue, Apr 6, 2021 at 1:32 PM Mark Brown <broonie@...nel.org> wrote:
> >
> > On Tue, Apr 06, 2021 at 01:26:51PM -0400, Jim Quinlan wrote:
> > > On Tue, Apr 6, 2021 at 12:47 PM Mark Brown <broonie@...nel.org> wrote:
> >
> > > > No great problem with having these in the controller node (assming it
> > > > accurately describes the hardware) but I do think we ought to also be
> > > > able to describe these per slot.

PCIe is effectively point to point, so there's only 1 slot unless 
there's a PCIe switch in the middle. If that's the case, then it's all 
more complicated.

> > > Can you explain what you think that would look like in the DT?
> >
> > I *think* that's just some properties on the nodes for the endpoints,
> > note that the driver could just ignore them for now.  Not sure where or
> > if we document any extensions but child nodes are in section 4 of the
> > v2.1 PCI bus binding.
> 
> Hi Mark,
> 
> I'm a little confused -- here is how I remember the chronology of the
> "DT bindings" commit reviews, please correct me if I'm wrong:
> 
> o JimQ submitted a pullreq for using voltage regulators in the same
> style as the existing "rockport" PCIe driver.
> o After some deliberation, RobH preferred that the voltage regulators
> should go into the PCIe subnode device's DT node.

IIRC, that's because you said there isn't a standard slot.

> o JimQ put the voltage regulators in the subnode device's DT node.
> o MarkB didn't like the fact that the code did a global search for the
> regulator since it could not provide the owning struct device* handle.
> o RobH relented, and said that if it is just two specific and standard
> voltage regulators, perhaps they can go in the parent DT node after
> all.
> o JimQ put the regulators back in the PCIe node.
> o MarkB now wants the regulators to go back into the child node again?
> 
> Folks, please advise.
> 
> Regards,
> Jim Quinlan
> Broadcom STB