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PCI: Generalize multi-function power dependency device links 

Although not allowed by the PCI specs, some multi-function devices have
power dependencies between the functions.  For example, function 1 may not
work unless function 0 is in the D0 power state.

The existing quirk_gpu_hda() adds a device link to express this dependency
for GPU and HDA devices, but it really is not specific to those device
types.

Generalize it and rename it to pci_create_device_link() so we can create
dependencies between any "consumer" and "producer" functions of a
multi-function device, where the consumer is only functional if the
producer is in D0.  This reorganization should not affect any
functionality.

Link: https://lore.kernel.org/lkml/20190606092225.17960-2-abhsahu@nvidia.com
Signed-off-by: Abhishek Sahu <abhsahu@nvidia.com>
[bhelgaas: commit log, reword diagnostic]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Abhishek Sahu 2019-06-06 14:52:24 +05:30 committed by Bjorn Helgaas
parent a188339ca5
commit a17beb1a08
1 changed files with 34 additions and 20 deletions
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54
drivers/pci/quirks.c
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@ -4934,35 +4934,49 @@ static void quirk_fsl_no_msi(struct pci_dev *pdev)
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, quirk_fsl_no_msi);
/*
* GPUs with integrated HDA controller for streaming audio to attached displays
* need a device link from the HDA controller (consumer) to the GPU (supplier)
* so that the GPU is powered up whenever the HDA controller is accessed.
* The GPU and HDA controller are functions 0 and 1 of the same PCI device.
* The device link stays in place until shutdown (or removal of the PCI device
* if it's hotplugged). Runtime PM is allowed by default on the HDA controller
* to prevent it from permanently keeping the GPU awake.
* Although not allowed by the spec, some multi-function devices have
* dependencies of one function (consumer) on another (supplier). For the
* consumer to work in D0, the supplier must also be in D0. Create a
* device link from the consumer to the supplier to enforce this
* dependency. Runtime PM is allowed by default on the consumer to prevent
* it from permanently keeping the supplier awake.
*/
static void quirk_gpu_hda(struct pci_dev *hda)
static void pci_create_device_link(struct pci_dev *pdev, unsigned int consumer,
unsigned int supplier, unsigned int class,
unsigned int class_shift)
{
struct pci_dev *gpu;
struct pci_dev *supplier_pdev;
if (PCI_FUNC(hda->devfn) != 1)
if (PCI_FUNC(pdev->devfn) != consumer)
return;
gpu = pci_get_domain_bus_and_slot(pci_domain_nr(hda->bus),
hda->bus->number,
PCI_DEVFN(PCI_SLOT(hda->devfn), 0));
if (!gpu || (gpu->class >> 16) != PCI_BASE_CLASS_DISPLAY) {
pci_dev_put(gpu);
supplier_pdev = pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
pdev->bus->number,
PCI_DEVFN(PCI_SLOT(pdev->devfn), supplier));
if (!supplier_pdev || (supplier_pdev->class >> class_shift) != class) {
pci_dev_put(supplier_pdev);
return;
}
if (!device_link_add(&hda->dev, &gpu->dev,
DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME))
pci_err(hda, "cannot link HDA to GPU %s\n", pci_name(gpu));
if (device_link_add(&pdev->dev, &supplier_pdev->dev,
DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME))
pci_info(pdev, "D0 power state depends on %s\n",
pci_name(supplier_pdev));
else
pci_err(pdev, "Cannot enforce power dependency on %s\n",
pci_name(supplier_pdev));
pm_runtime_allow(&hda->dev);
pci_dev_put(gpu);
pm_runtime_allow(&pdev->dev);
pci_dev_put(supplier_pdev);
}
/*
* Create device link for GPUs with integrated HDA controller for streaming
* audio to attached displays.
*/
static void quirk_gpu_hda(struct pci_dev *hda)
{
pci_create_device_link(hda, 1, 0, PCI_BASE_CLASS_DISPLAY, 16);
}
DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_ATI, PCI_ANY_ID,
PCI_CLASS_MULTIMEDIA_HD_AUDIO, 8, quirk_gpu_hda);