From: Bjorn Helgaas <helgaas@kernel.org>
To: Heiner Kallweit <hkallweit1@gmail.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Kai Heng Feng <kai.heng.feng@canonical.com>,
Lukas Wunner <lukas@wunner.de>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Time to re-enable Runtime PM per default for PCI devcies?
Date: Tue, 17 Nov 2020 10:38:17 -0600 [thread overview]
Message-ID: <20201117163817.GA1397220@bjorn-Precision-5520> (raw)
In-Reply-To: <79940973-b631-90f9-dbc4-9579c6000816@gmail.com>
[+to Rafael, author of the commit you mentioned,
+cc Mika, Kai Heng, Lukas, linux-pm, linux-kernel]
On Tue, Nov 17, 2020 at 04:56:09PM +0100, Heiner Kallweit wrote:
> More than 10 yrs ago Runtime PM was disabled per default by bb910a7040
> ("PCI/PM Runtime: Make runtime PM of PCI devices inactive by default").
>
> Reason given: "avoid breakage on systems where ACPI-based wake-up is
> known to fail for some devices"
> Unfortunately the commit message doesn't mention any affected devices
> or systems.
>
> With Runtime PM disabled e.g. the PHY on network devices may remain
> powered up even with no cable plugged in, affecting battery lifetime
> on mobile devices. Currently we have to rely on the respective distro
> or user to enable Runtime PM via sysfs (echo auto > power/control).
> Some devices work around this restriction by calling pm_runtime_allow
> in their probe routine, even though that's not recommended by
> https://www.kernel.org/doc/Documentation/power/pci.txt
>
> Disabling Runtime PM per default seems to be a big hammer, a quirk
> for affected devices / systems may had been better. And we still
> have the option to disable Runtime PM for selected devices via sysfs.
>
> So, to cut a long story short: Wouldn't it be time to remove this
> restriction?
I don't know the history of this, but maybe Rafael or the others can
shed some light on it.
next prev parent reply other threads:[~2020-11-17 16:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 15:56 Time to re-enable Runtime PM per default for PCI devcies? Heiner Kallweit
2020-11-17 16:38 ` Bjorn Helgaas [this message]
2020-11-17 16:57 ` Rafael J. Wysocki
2020-12-26 15:26 ` Heiner Kallweit
2020-12-29 11:56 ` Kai-Heng Feng
2020-12-29 21:11 ` Heiner Kallweit
2020-12-30 22:56 ` Heiner Kallweit
2020-12-31 4:07 ` Lukas Wunner
2020-12-31 9:38 ` Heiner Kallweit
2020-12-31 9:52 ` Heiner Kallweit
2021-01-04 17:39 ` Lukas Wunner
2021-01-04 20:32 ` Heiner Kallweit
2020-12-29 11:30 ` Lukas Wunner
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