When cutting power to a GPU and its integrated HDA controller, their
cached current_state should be updated to D3cold to reflect reality.
We currently rely on the DRM and HDA drivers to do that, however:
- The HDA driver updates the current_state in azx_vs_set_state(), which
will no longer be called with driver power control once we migrate to
device links. (It will still be called with manual power control.)
- If the HDA device is not bound, its current_state remains at D0 even
though the GPU driver may decide to go to D3cold.
- The DRM drivers update the current_state using pci_set_power_state()
which can't put the device into a deeper power state than D3hot if the
GPU is not deemed power-manageable by the platform (even though it
*is* power-manageable by some nonstandard means, such as a _DSM).
Centralize updating the current_state of the GPU and HDA controller in
vga_switcheroo's ->runtime_suspend hook to overcome these deficiencies.
The GPU and HDA controller are two functions of the same PCI device
(VGA class device on function 0 and audio device on function 1) and
no other PCI devices reside on the same bus since this is a PCIe
point-to-point link, so we can just walk the bus and update the
current_state of all devices.
On ->runtime_resume, the HDA controller is in D0uninitialized state.
Resume to D0active and then let it autosuspend as it sees fit.
Note that vga_switcheroo_init_domain_pm_ops() is not supposed to be
called by hybrid graphics laptops which power down the GPU via its root
port's _PR3 resources and consequently vga_switcheroo_runtime_suspend()
is not used. On those laptops, the root port is power-manageable by the
platform (instead of by a nonstandard means) and the current_state is
therefore updated by the PCI core through the following call chain:
pci_set_power_state()
__pci_complete_power_transition()
pci_bus_set_current_state()
Resuming to D0active happens through:
pci_set_power_state()
__pci_start_power_transition()
pci_wakeup_bus()
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxx>
Cc: Peter Wu <peter@xxxxxxxxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
---
drivers/gpu/vga/vga_switcheroo.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index 3cd153c6d271..09dd40dd1dbe 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -1022,6 +1022,7 @@ static int vga_switcheroo_runtime_suspend(struct device *dev)
vgasr_priv.handler->switchto(VGA_SWITCHEROO_IGD);
mutex_unlock(&vgasr_priv.mux_hw_lock);
}
+ pci_bus_set_current_state(pdev->bus, PCI_D3cold);
vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_OFF);
mutex_unlock(&vgasr_mutex);
return 0;
@@ -1035,6 +1036,7 @@ static int vga_switcheroo_runtime_resume(struct device *dev)
mutex_lock(&vgasr_mutex);
vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_ON);
mutex_unlock(&vgasr_mutex);
+ pci_wakeup_bus(pdev->bus);
ret = dev->bus->pm->runtime_resume(dev);
if (ret)
return ret;
--
2.15.1
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