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

[Dave Airlie]

On 11 March 2016 at 23:45, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> On Friday, March 11, 2016 12:58:15 PM Mika Westerberg wrote:
>> 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.
>
> Right, after your patches have been applied, the additional handling
> won't be needed.
>
> So Dave, maybe you can check if the Mika's patches help?

Hi Mika,

I tested your patches with a couple of changes on the Lenovo W541.

The attached patch contains the two things I needed to get the same
functionality
as my patches.

I'm really not in love with the per-chipset enablement for this,
really any chipsets
after a certain year should probably be better, as we'll constantly be
adding PCI Ids
for every chipset ever made, and I expect we'll forget some.

Dave.
From eea412076c9d24262ebd4811f766d5379b728045 Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied@xxxxxxxxxx>
Date: Mon, 14 Mar 2016 23:37:43 +1000
Subject: [PATCH] [RFC] PCI: enable runtime PM on pcieports to let secondary
 GPUs powerdown.

With secondary GPUs in Windows 10 laptops we need to use runtime PM
to power down the PCIe ports after the devices goes to D3Cold.

This patch adds the PCI ID for the Haswell 16x PCIE slot found
in the W541 laptops. I should probably try and gather the PCI IDs,
for broadwell/skylake variants as well if we can't find them.

This fixes a regression on W541 laptops on top of Mika's PCIE patches
since we started advertising Windows 2013 ACPI.

[probably should be two patches - hence RFC]

Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
---
 drivers/pci/pcie/portdrv_pci.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index 43dd23e..1405de8 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -278,8 +278,10 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
 
 	pci_save_state(dev);
 
-	if (pcie_port_runtime_suspend_allowed(dev))
+	if (pcie_port_runtime_suspend_allowed(dev)) {
+		pm_runtime_allow(&dev->dev);
 		pm_runtime_put_noidle(&dev->dev);
+	}
 
 	return 0;
 }
@@ -436,6 +438,8 @@ static void pcie_portdrv_err_resume(struct pci_dev *dev)
  * LINUX Device Driver Model
  */
 static const struct pci_device_id port_pci_ids[] = {
+	/* Intel Skylake PCIE graphics port */
+	{ PCI_VDEVICE(INTEL, 0x0c01), .driver_data = PCIE_PORT_SPT },
 	/* Intel Broxton */
 	{ PCI_VDEVICE(INTEL, 0x1ad6), .driver_data = PCIE_PORT_SPT },
 	{ PCI_VDEVICE(INTEL, 0x1ad7), .driver_data = PCIE_PORT_SPT },
-- 
2.5.0