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PCI: Add NVIDIA GPU multi-function power dependencies 

The NVIDIA Turing GPU is a multi-function PCI device with the following
functions:

  - Function 0: VGA display controller
  - Function 1: Audio controller
  - Function 2: USB xHCI Host controller
  - Function 3: USB Type-C UCSI controller

Function 0 is tightly coupled with other functions in the hardware.  When
function 0 is in D3, it gates power for hardware blocks used by other
functions, which means those functions only work when function 0 is in D0.
If any of these functions (1/2/3) are in D0, then function 0 should also be
in D0.

Commit 07f4f97d7b ("vga_switcheroo: Use device link for HDA controller")
already creates a device link to show the dependency of function 1 on
function 0 of this GPU.  Create additional device links to express the
dependencies of functions 2 and 3 on function 0.  This means function 0
will be in D0 if any other function is in D0.

[bhelgaas: I think the PCI spec expectation is that functions can be
power-managed independently, so I don't think this device is technically
compliant.  For example, the PCIe r5.0 spec, sec 1.4, says "the PCI/PCIe
hardware/software model includes architectural constructs necessary to
discover, configure, and use a Function, without needing Function-specific
knowledge" and sec 5.1 says "D states are associated with a particular
Function" and "PM provides ... a mechanism to identify power management
capabilities of a given Function [and] the ability to transition a Function
into a certain power management state."]

Link: https://lore.kernel.org/lkml/20190606092225.17960-3-abhsahu@nvidia.com
Signed-off-by: Abhishek Sahu <abhsahu@nvidia.com>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Abhishek Sahu 2019-06-06 14:52:25 +05:30 committed by Bjorn Helgaas
parent a17beb1a08
commit 6d2e369f0d
1 changed files with 26 additions and 0 deletions
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26
drivers/pci/quirks.c
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@ -4985,6 +4985,32 @@ DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_AMD, PCI_ANY_ID,
DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
PCI_CLASS_MULTIMEDIA_HD_AUDIO, 8, quirk_gpu_hda);
/*
* Create device link for NVIDIA GPU with integrated USB xHCI Host
* controller to VGA.
*/
static void quirk_gpu_usb(struct pci_dev *usb)
{
pci_create_device_link(usb, 2, 0, PCI_BASE_CLASS_DISPLAY, 16);
}
DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
PCI_CLASS_SERIAL_USB, 8, quirk_gpu_usb);
/*
* Create device link for NVIDIA GPU with integrated Type-C UCSI controller
* to VGA. Currently there is no class code defined for UCSI device over PCI
* so using UNKNOWN class for now and it will be updated when UCSI
* over PCI gets a class code.
*/
#define PCI_CLASS_SERIAL_UNKNOWN 0x0c80
static void quirk_gpu_usb_typec_ucsi(struct pci_dev *ucsi)
{
pci_create_device_link(ucsi, 3, 0, PCI_BASE_CLASS_DISPLAY, 16);
}
DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
PCI_CLASS_SERIAL_UNKNOWN, 8,
quirk_gpu_usb_typec_ucsi);
/*
* Some IDT switches incorrectly flag an ACS Source Validation error on
* completions for config read requests even though PCIe r4.0, sec