From: Lukas Wunner <lukas@wunner.de>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
Kai Heng Feng <kai.heng.feng@canonical.com>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
linux-pci@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Mathias Nyman <mathias.nyman@intel.com>,
linux-usb@vger.kernel.org
Subject: Re: [PATCH] PCI / PM: Don't runtime suspend when device only supports wakeup from D0
Date: Wed, 22 May 2019 20:53:39 +0200 [thread overview]
Message-ID: <20190522185339.pfo5xeopyz2i5iem@wunner.de> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1905221433310.1410-100000@iolanthe.rowland.org>
On Wed, May 22, 2019 at 02:39:56PM -0400, Alan Stern wrote:
> According to Kai, PME signalling doesn't work in D0 -- or at least, it
> is _documented_ not to work in D0 -- even though it is enabled and the
> device claims to support it.
>
> In any case, I don't really see any point in "runtime suspending" a
> device while leaving it in D0. We might as well just leave it alone.
There may be devices whose drivers are able to reduce power consumption
through some device-specific means when runtime suspending, even though
the device remains in PCI_D0. The patch would cause a power regression
for those.
In particular, pci_target_state() returns PCI_D0 if the device lacks the
PM capability.
Thanks,
Lukas
next prev parent reply other threads:[~2019-05-22 18:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190521163104.15759-1-kai.heng.feng@canonical.com>
2019-05-21 22:23 ` [PATCH] PCI / PM: Don't runtime suspend when device only supports wakeup from D0 Bjorn Helgaas
2019-05-22 3:42 ` Kai Heng Feng
2019-05-22 13:48 ` Bjorn Helgaas
2019-05-22 15:46 ` Kai Heng Feng
2019-05-22 18:11 ` Bjorn Helgaas
2019-05-22 18:39 ` Alan Stern
2019-05-22 18:53 ` Lukas Wunner [this message]
2019-05-22 19:05 ` Kai Heng Feng
2019-05-22 20:52 ` Bjorn Helgaas
2019-05-23 4:39 ` Kai-Heng Feng
2019-05-27 16:57 ` Bjorn Helgaas
2019-06-05 11:57 ` Bjorn Helgaas
2019-07-05 7:02 ` Kai-Heng Feng
2019-07-05 9:39 ` Rafael J. Wysocki
2019-07-05 13:51 ` Kai-Heng Feng
2019-07-09 13:45 ` Bjorn Helgaas
2019-09-02 13:47 ` Kai-Heng Feng
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