@@ -618,6 +618,64 @@ nouveau_drm_device_fini(struct drm_device *dev)
kfree(drm);
}
+/*
+ * On some Intel PCIe bridge controllers doing a
+ * D0 -> D3hot -> D3cold -> D0 sequence causes Nvidia GPUs to not reappear.
+ * Skipping the intermediate D3hot step seems to make it work again. This is
+ * probably caused by not meeting the expectation the involved AML code has
+ * when the GPU is put into D3hot state before invoking it.
+ *
+ * This leads to various manifestations of this issue:
+ * - AML code execution to power on the GPU hits an infinite loop (as the
+ * code waits on device memory to change).
+ * - kernel crashes, as all PCI reads return -1, which most code isn't able
+ * to handle well enough.
+ *
+ * In all cases dmesg will contain at least one line like this:
+ * 'nouveau 0000:01:00.0: Refused to change power state, currently in D3'
+ * followed by a lot of nouveau timeouts.
+ *
+ * In the \_SB.PCI0.PEG0.PG00._OFF code deeper down writes bit 0x80 to the not
+ * documented PCI config space register 0x248 of the Intel PCIe bridge
+ * controller (0x1901) in order to change the state of the PCIe link between
+ * the PCIe port and the GPU. There are alternative code paths using other
+ * registers, which seem to work fine (executed pre Windows 8):
+ * - 0xbc bit 0x20 (publicly available documentation claims 'reserved')
+ * - 0xb0 bit 0x10 (link disable)
+ * Changing the conditions inside the firmware by poking into the relevant
+ * addresses does resolve the issue, but it seemed to be ACPI private memory
+ * and not any device accessible memory at all, so there is no portable way of
+ * changing the conditions.
+ * On a XPS 9560 that means bits [0,3] on \CPEX need to be cleared.
+ *
+ * The only systems where this behavior can be seen are hybrid graphics laptops
+ * with a secondary Nvidia Maxwell, Pascal or Turing GPU. It's unclear whether
+ * this issue only occurs in combination with listed Intel PCIe bridge
+ * controllers and the mentioned GPUs or other devices as well.
+ *
+ * documentation on the PCIe bridge controller can be found in the
+ * "7th Generation Intel® Processor Families for H Platforms Datasheet Volume 2"
+ * Section "12 PCI Express* Controller (x16) Registers"
+ */
+
+static void quirk_broken_nv_runpm(struct pci_dev *pdev)
+{
+ struct drm_device *dev = pci_get_drvdata(pdev);
+ struct nouveau_drm *drm = nouveau_drm(dev);
+ struct pci_dev *bridge = pci_upstream_bridge(pdev);
+
+ if (!bridge || bridge->vendor != PCI_VENDOR_ID_INTEL)
+ return;
+
+ switch (bridge->device) {
+ case 0x1901:
+ drm->old_pm_cap = pdev->pm_cap;
+ pdev->pm_cap = 0;
+ NV_INFO(drm, "Disabling PCI power management to avoid bug\n");
+ break;
+ }
+}
+
static int nouveau_drm_probe(struct pci_dev *pdev,
const struct pci_device_id *pent)
{
@@ -699,6 +757,7 @@ static int nouveau_drm_probe(struct pci_dev *pdev,
if (ret)
goto fail_drm_dev_init;
+ quirk_broken_nv_runpm(pdev);
return 0;
fail_drm_dev_init:
@@ -736,7 +795,11 @@ static void
nouveau_drm_remove(struct pci_dev *pdev)
{
struct drm_device *dev = pci_get_drvdata(pdev);
+ struct nouveau_drm *drm = nouveau_drm(dev);
+ /* revert our workaround */
+ if (drm->old_pm_cap)
+ pdev->pm_cap = drm->old_pm_cap;
nouveau_drm_device_remove(dev);
}
@@ -138,6 +138,8 @@ struct nouveau_drm {
struct list_head clients;
+ u8 old_pm_cap;
+
struct {
struct agp_bridge_data *bridge;
u32 base;