From: Bjorn Helgaas <helgaas@kernel.org>
To: "Deucher, Alexander" <Alexander.Deucher@amd.com>
Cc: Lukas Wunner <lukas@wunner.de>, Huacai Chen <chenhc@lemote.com>,
Bjorn Helgaas <bhelgaas@google.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
Huacai Chen <chenhuacai@gmail.com>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH 1/2] PCI/portdrv: Remove the .remove() method in pcie_portdriver
Date: Mon, 14 Sep 2020 17:03:50 -0500 [thread overview]
Message-ID: <20200914220350.GA1312933@bjorn-Precision-5520> (raw)
In-Reply-To: <MN2PR12MB44881AF114C47613285A083BF7230@MN2PR12MB4488.namprd12.prod.outlook.com>
[+cc Rafael]
On Mon, Sep 14, 2020 at 08:34:03PM +0000, Deucher, Alexander wrote:
> FWIW, our newer GPUs have both upstream and downstream ports that
> are part of the device.
>
> Slightly off topic, but does the current pm code handle these cases
> correctly? ACPI related power handling doesn't seem to work
> correctly for these devices in laptops where the GPU power control
> is handled by ACPI.
I guess these newer GPUs basically have a PCIe switch embedded in
them? The picture in my head is this:
+--------------------------------------+
+----+ |+--------+ +----------+ +--------+|
|Root+------+Switch +---+Switch +---+GPU ||
|Port| ||Upstream| |Downstream| |Endpoint||
+----+ ||Port | |Port | | ||
|+--------+ +----------+ +--------+|
+--------------------------------------+
Is that accurate? If not, can you share "lspci -vv" output so we can
figure it out?
The PCI PM code is *supposed* to work with arbitrary hierarchies, so
assuming your devices are PCIe spec-compliant, it should work.
It sounds like ACPI PM is involved as well, and I can't speak to that
side at all. But I know Rafael can :)
Bjorn
next prev parent reply other threads:[~2020-09-14 22:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-11 10:09 [PATCH 1/2] PCI/portdrv: Remove the .remove() method in pcie_portdriver Huacai Chen
2020-09-11 10:09 ` [PATCH 2/2] PCI/portdrv: Don't disable pci device during shutdown Huacai Chen
2020-09-13 16:04 ` Bjorn Helgaas
2020-09-14 20:43 ` Deucher, Alexander
2020-09-13 5:01 ` [PATCH 1/2] PCI/portdrv: Remove the .remove() method in pcie_portdriver Lukas Wunner
2020-09-13 15:42 ` Bjorn Helgaas
2020-09-14 20:34 ` Deucher, Alexander
2020-09-14 22:03 ` Bjorn Helgaas [this message]
2020-09-15 2:50 ` Lukas Wunner
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