From: Bjorn Helgaas <helgaas@kernel.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Dilip Kota <eswara.kota@linux.intel.com>,
Andrew Murray <andrew.murray@arm.com>,
Jingoo Han <jingoohan1@gmail.com>,
gustavo.pimentel@synopsys.com,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Rob Herring <robh@kernel.org>,
martin.blumenstingl@googlemail.com,
Linux PCI <linux-pci@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Shevchenko, Andriy" <andriy.shevchenko@intel.com>,
cheol.yong.kim@intel.com, chuanhua.lei@linux.intel.com,
qi-ming.wu@intel.com, Linux PM <linux-pm@vger.kernel.org>,
Rajat Jain <rajatja@google.com>,
Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [PATCH v4 3/3] pci: intel: Add sysfs attributes to configure pcie link
Date: Thu, 31 Oct 2019 08:01:30 -0500 [thread overview]
Message-ID: <20191031130130.GA37287@google.com> (raw)
In-Reply-To: <5652130.irlrSN52DS@kreacher>
On Thu, Oct 31, 2019 at 10:13:11AM +0100, Rafael J. Wysocki wrote:
> On Thursday, October 31, 2019 3:56:37 AM CET Bjorn Helgaas wrote:
> > On Thu, Oct 31, 2019 at 12:31:44AM +0100, Rafael J. Wysocki wrote:
> > > On Wed, Oct 30, 2019 at 11:14 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > > Rafael had some concerns about the proposed ASPM interface [2], but I
> > > > don't know what they are yet.
> > >
> > > I was talking about the existing ASPM interface in sysfs. The new one
> > > I still have to review, but I'm kind of wondering what about people
> > > who used the old one? Would it be supported going forward?
> >
> > The old one interface was enabled by CONFIG_PCIEASPM_DEBUG. Red Hat
> > doesn't enable that. Ubuntu does. I *thought* we heard from a
> > Canonical person who said they didn't have any tools that used it, but
> > I can't find that now. I don't know about SUSE.
> >
> > So the idea was to drop it on the theory that nobody is using it.
> > Possibly that's too aggressive.
>
> Well, one problem is that the "old" (actually existing) I/F has made it
> to one of my OSS EU presentation slides (I did not talk to this particular
> slide, but it is there in the deck that's available for downloading), so who
> knows who is going to use it. :-)
>
> So I guess that there's a risk that needs to be taken into consideration.
>
> What could be done, in principle, would be to make the new I/F depend on
> CONFIG_PCIEASPM_DEBUG being unset and provide the "old" one when it is set.
I would prefer to enable the new interface unconditionally to make it
easier for userspace tools like powertop to use it.
I think the existing and new interfaces could coexist, with the
existing interface being enabled by CONFIG_PCIEASPM_DEBUG as it is
today. The patch that removes the existing interface is the last in
the series and could easily be dropped.
> In any case, the pcie_aspm.policy module parameter cannot be dropped, because
> AFAICS there is quite a bit of user space using it (e.g. TLP).
What is TLP? Since CONFIG_PCIEASPM is a bool, aspm.o is built in
statically if enabled, so pcie_aspm.policy is effectively a boot-time
kernel parameter, right? We don't have a plan to remove it.
Bjorn
next prev parent reply other threads:[~2019-10-31 13:01 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-21 6:39 [PATCH v4 0/3] PCI: Add Intel PCIe Driver and respective dt-binding yaml file Dilip Kota
2019-10-21 6:39 ` [PATCH v4 1/3] dt-bindings: PCI: intel: Add YAML schemas for the PCIe RC controller Dilip Kota
2019-10-21 11:19 ` Andrew Murray
2019-10-22 10:15 ` Dilip Kota
2019-10-24 20:31 ` Martin Blumenstingl
2019-10-29 7:53 ` Dilip Kota
2019-10-25 16:53 ` Rob Herring
2019-10-29 8:34 ` Dilip Kota
2019-10-31 10:51 ` Dilip Kota
2019-10-31 18:35 ` Rob Herring
2019-10-21 6:39 ` [PATCH v4 2/3] dwc: PCI: intel: PCIe RC controller driver Dilip Kota
2019-10-21 8:29 ` Gustavo Pimentel
2019-10-21 10:44 ` Dilip Kota
2019-10-22 10:18 ` Dilip Kota
2019-10-22 11:44 ` andriy.shevchenko
2019-10-25 9:01 ` Andrew Murray
2019-10-29 6:14 ` Dilip Kota
2019-10-21 13:03 ` Andrew Murray
2019-10-22 9:04 ` Dilip Kota
2019-10-25 9:09 ` Andrew Murray
2019-10-29 8:59 ` Dilip Kota
2019-11-01 10:59 ` Andrew Murray
2019-11-04 9:34 ` Dilip Kota
2019-11-04 10:47 ` Andrew Murray
2019-10-21 17:17 ` Bjorn Helgaas
2019-10-22 9:07 ` Dilip Kota
2019-10-22 13:09 ` Bjorn Helgaas
2019-10-29 7:45 ` Dilip Kota
2019-10-25 13:11 ` kbuild test robot
2019-10-25 13:11 ` [RFC PATCH] dwc: PCI: intel: intel_pcie_msi_init() can be static kbuild test robot
2019-10-21 6:39 ` [PATCH v4 3/3] pci: intel: Add sysfs attributes to configure pcie link Dilip Kota
2019-10-21 8:40 ` Gustavo Pimentel
2019-10-21 10:34 ` Dilip Kota
2019-10-21 13:38 ` Andrew Murray
2019-10-21 17:18 ` Bjorn Helgaas
2019-10-22 9:27 ` Dilip Kota
2019-10-22 12:59 ` Bjorn Helgaas
2019-10-29 9:31 ` Dilip Kota
2019-10-30 22:14 ` Bjorn Helgaas
2019-10-30 23:31 ` Rafael J. Wysocki
2019-10-31 2:56 ` Bjorn Helgaas
2019-10-31 9:13 ` Rafael J. Wysocki
2019-10-31 13:01 ` Bjorn Helgaas [this message]
2019-10-31 10:47 ` Dilip Kota
2019-10-31 13:22 ` Bjorn Helgaas
2019-11-01 5:47 ` Dilip Kota
2019-11-01 11:30 ` Andrew Murray
2019-10-29 10:42 ` Rafael J. Wysocki
2019-10-29 12:36 ` Bjorn Helgaas
2019-10-22 9:20 ` Dilip Kota
2019-10-25 9:34 ` Andrew Murray
2019-10-29 9:51 ` Dilip Kota
2019-10-21 8:08 ` [PATCH v4 0/3] PCI: Add Intel PCIe Driver and respective dt-binding yaml file Gustavo Pimentel
2019-10-21 8:31 ` Dilip Kota
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