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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Bjorn Helgaas <bhelgaas@google.com>, Len Brown <lenb@kernel.org>,
	Lukas Wunner <lukas@wunner.de>,
	Keith Busch <keith.busch@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Alexandru Gagniuc <mr.nuke.me@gmail.com>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Linux PCI <linux-pci@vger.kernel.org>
Subject: Re: [PATCH v2 0/3] PCI / ACPI: Handle sibling devices sharing power resources
Date: Wed, 19 Jun 2019 15:24:40 +0200
Message-ID: <CAJZ5v0gD2sCBKv4QXWSOg+smQryqamCaYUbVQZeMSpCoA1rkVg@mail.gmail.com> (raw)
In-Reply-To: <20190618161858.77834-1-mika.westerberg@linux.intel.com>

On Tue, Jun 18, 2019 at 6:19 PM Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
>
> Hi all,
>
> Based on a discussion regarding patch series I sent previously [1] to deal
> with sibling devices sharing ACPI power resources, I prepared a new
> reworked version according to the comments I got.
>
> To summarize, in Intel Ice Lake the Thunderbolt controller, PCIe root ports
> and xHCI all share power resources. When they are all in D3hot power
> resources (returned by _PR3) can be turned off powering off the whole
> block. However, there are two issues around this.
>
> Firstly the PCI core sets the device power state by asking what the real
> ACPI power state is. This results that all but last device sharing the
> power resources are in D3hot when the power resources are turned off. This
> causes issues if user runs for example 'lspci' because the device is really
> in D3cold so what user gets back is all ones (0xffffffff).
>
> Secondly if any of the device is runtime resumed the power resources are
> turned on bringing all other devices sharing the resources to
> D0uninitialized losing their wakeup configuration.
>
> This series aims to fix the two issues by:
>
>   1. Using the ACPI cached power state when PCI devices are transitioned
>      into low power states instead of reading back the "real" power state.
>
>   2. Introducing concept of "_PR0 dependent devices" that get runtime
>      resumed whenever their power resource (which they might share with
>      other sibling devices) gets turned on.
>
> The series is based on the idea of Rafael J. Wysocki <rafael@kernel.org>.
>
> [1] https://www.spinics.net/lists/linux-pci/msg83583.html
>
> Mika Westerberg (3):
>   PCI / ACPI: Use cached ACPI device state to get PCI device power state
>   ACPI / PM: Introduce concept of a _PR0 dependent device
>   PCI / ACPI: Add _PR0 dependent devices

LGMT overall, patch [2/3] can be simplified slightly IMO (already sent
comments for that one).

As far as I'm concerned, the other patches need not be updated.

      parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-18 16:18 Mika Westerberg
2019-06-18 16:18 ` [PATCH v2 1/3] PCI / ACPI: Use cached ACPI device state to get PCI device power state Mika Westerberg
2019-06-19 21:28   ` Bjorn Helgaas
2019-06-20  8:27     ` Mika Westerberg
2019-06-20 13:16       ` Bjorn Helgaas
2019-06-20 13:37         ` Mika Westerberg
2019-06-20 14:15           ` Bjorn Helgaas
2019-06-21 10:32             ` Rafael J. Wysocki
2019-06-21 13:09               ` Bjorn Helgaas
2019-06-22  8:51                 ` Rafael J. Wysocki
2019-06-24 10:57                   ` Mika Westerberg
2019-06-24 11:14               ` Rafael J. Wysocki
2019-06-25  9:45                 ` Mika Westerberg
2019-06-25 10:00                   ` Rafael J. Wysocki
2019-06-25 10:08                     ` Mika Westerberg
2019-06-21 11:56   ` Rafael J. Wysocki
2019-06-24 10:58     ` Mika Westerberg
2019-06-18 16:18 ` [PATCH v2 2/3] ACPI / PM: Introduce concept of a _PR0 dependent device Mika Westerberg
2019-06-19 13:20   ` Rafael J. Wysocki
2019-06-19 13:34     ` Mika Westerberg
2019-06-18 16:18 ` [PATCH v2 3/3] PCI / ACPI: Add _PR0 dependent devices Mika Westerberg
2019-06-19 13:24 ` Rafael J. Wysocki [this message]

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