From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Linux PM <linux-pm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux ACPI <linux-acpi@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH] PM: sleep: core: Fix the handling of pending runtime resume requests
Date: Mon, 24 Aug 2020 15:38:39 +0200 [thread overview]
Message-ID: <2486532.D7zGhtygOF@kreacher> (raw)
In-Reply-To: <20200824083452.GX1375436@lahna.fi.intel.com>
On Monday, August 24, 2020 10:34:52 AM CEST Mika Westerberg wrote:
> Hi,
>
> On Fri, Aug 21, 2020 at 03:34:42PM -0400, Alan Stern wrote:
> > This means that the code could be simplified to just:
> >
> > pm_runtime_barrier(dev);
> >
> > Will this fix the reported bug? It seems likely to me that the actual
> > problem with the failure scenario in the patch description was that
> > turning on an ACPI power resource causes runtime-resume requests to be
> > queued for all devices sharing that resource. Wouldn't it make more
> > sense to resume only the device that requested it and leave the others
> > in runtime suspend?
>
> The problem with at least PCIe devices that share ACPI power resources
> is that once you turn on the power resource all the devices that shared
> it will go into D0uninitialized power state and that means they lose all
> wake configuration etc. so they need to be re-initialized by their
> driver before they can go back to D3(cold) in order for their wakes to
> still work.
Plus devices in D0uninitialized may prevent the SoC from allowing package
C-states to be used for the processor AFAICS.
BTW, does the patch make the issue at hand go away?
next prev parent reply other threads:[~2020-08-24 13:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 17:41 [PATCH] PM: sleep: core: Fix the handling of pending runtime resume requests Rafael J. Wysocki
2020-08-21 19:34 ` Alan Stern
2020-08-24 8:34 ` Mika Westerberg
2020-08-24 13:38 ` Rafael J. Wysocki [this message]
2020-08-24 13:59 ` Mika Westerberg
2020-08-24 13:36 ` Rafael J. Wysocki
2020-08-24 15:04 ` Alan Stern
2020-08-24 17:31 ` Rafael J. Wysocki
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