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@redhat.com Cc: Ben Skeggs bskeggs@redhat.com Cc: Takashi Iwai tiwai@suse.de Cc: Peter Wu peter@lekensteyn.nl Cc: Alex Deucher alexander.deucher@amd.com Cc: Bjorn Helgaas bhelgaas@google.com Cc: Rafael J. Wysocki rafael.j.wysocki@intel.com Tested-by: Mike Lothian mike@fireburn.co.uk Signed-off-by: Lukas Wunner lukas@wunner.de --- 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;