linux-kernel - Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines.

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Date:	Fri, 11 Mar 2016 12:58:15 +0200
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Dave Airlie <airlied@...il.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10
 machines.

On Thu, Mar 10, 2016 at 09:57:09PM +0100, Rafael J. Wysocki wrote:
> > It doesn't seem to do any runtime PM,
> > I do wonder if pcieport should be doing it's own runtime PM handling,
> > but that is a
> > larger task than I'm thinking to tackle here.
> 
> PCIe ports don't do PM - yet.  Mika has posted a series of patches to implement
> that, however, that are waiting for comments now:
> 
> https://patchwork.kernel.org/patch/8453311/
> https://patchwork.kernel.org/patch/8453381/
> https://patchwork.kernel.org/patch/8453391/
> https://patchwork.kernel.org/patch/8453411/
> https://patchwork.kernel.org/patch/8453371/
> https://patchwork.kernel.org/patch/8453351/
> 
> > Maybe I should be doing
> > 
> > pci_set_power_state(pdev->bus->self, PCI_D3cold) ? I'm not really sure.
> 
> Using pci_set_power_state() would be more appropriate IMO, but you can get
> to the bridge via dev->parent too, can't you?
> 
> In any case, it looks like you and Mika need to talk. :-)

When the vga_switcheroo device gets runtime suspended (with the above
runtime PM patchs for PCIe root ports) the root port should also be
runtime suspended by the PM core. I don't think there is a need to call
any pci_set_power_state() in this driver but maybe I'm missing
something.