From: Bjorn Helgaas <helgaas@kernel.org>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
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>,
linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH v2 1/3] PCI / ACPI: Use cached ACPI device state to get PCI device power state
Date: Wed, 19 Jun 2019 16:28:01 -0500 [thread overview]
Message-ID: <20190619212801.GC143205@google.com> (raw)
In-Reply-To: <20190618161858.77834-2-mika.westerberg@linux.intel.com>
On Tue, Jun 18, 2019 at 07:18:56PM +0300, Mika Westerberg wrote:
> Intel Ice Lake has an integrated Thunderbolt controller which means that
> the PCIe topology is extended directly from the two root ports (RP0 and
> RP1).
A PCIe topology is always extended directly from root ports,
regardless of whether a Thunderbolt controller is integrated, so I
guess I'm missing the point you're making. It doesn't sound like this
is anything specific to Thunderbolt?
> Power management is handled by ACPI power resources that are
> shared between the root ports, Thunderbolt controller (NHI) and xHCI
> controller.
>
> The topology with the power resources (marked with []) looks like:
>
> Host bridge
> |
> +- RP0 ---\
> +- RP1 ---|--+--> [TBT]
> +- NHI --/ |
> | |
> | v
> +- xHCI --> [D3C]
>
> Here TBT and D3C are the shared ACPI power resources. ACPI _PR3() method
> returns either TBT or D3C or both.
>
> Say we runtime suspend first the root ports RP0 and RP1, then NHI. Now
> since the TBT power resource is still on when the root ports are runtime
> suspended their dev->current_state is set to D3hot. When NHI is runtime
> suspended TBT is finally turned off but state of the root ports remain
> to be D3hot.
>
> If the user now runs lspci for instance, the result is all 1's like in
> the below output (07.0 is the first root port, RP0):
>
> 00:07.0 PCI bridge: Intel Corporation Device 8a1d (rev ff) (prog-if ff)
> !!! Unknown header type 7f
> Kernel driver in use: pcieport
>
> I short the hardware state is not in sync with the software state
> anymore. The exact same thing happens with the PME polling thread which
> ends up bringing the root ports back into D0 after they are runtime
> suspended.
s/I /In /
next prev parent reply other threads:[~2019-06-19 21:28 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-18 16:18 [PATCH v2 0/3] PCI / ACPI: Handle sibling devices sharing power resources 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 [this message]
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 ` [PATCH v2 0/3] PCI / ACPI: Handle sibling devices sharing power resources Rafael J. Wysocki
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