[v7] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges

Message ID	20200310192627.437947-1-kherbst@redhat.com
State	New
Headers	show Return-Path: <linux-pci-owner@vger.kernel.org> From: Karol Herbst <kherbst@redhat.com> To: linux-kernel@vger.kernel.org Cc: Karol Herbst <kherbst@redhat.com>, Bjorn Helgaas <bhelgaas@google.com>, Lyude Paul <lyude@redhat.com>, "Rafael J . Wysocki" <rjw@rjwysocki.net>, Mika Westerberg <mika.westerberg@intel.com>, linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, Mika Westerberg <mika.westerberg@linux.intel.com> Subject: [PATCH v7] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges Date: Tue, 10 Mar 2020 20:26:27 +0100 Message-Id: <20200310192627.437947-1-kherbst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-pci-owner@vger.kernel.org Precedence: bulk
Series	[v7] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges \| expand [v7] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges

diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index b65ae817eabf..2c86f0248305 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -618,6 +618,60 @@ 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 *dev) +{ + struct pci_dev *bridge = pci_upstream_bridge(dev); + + if (!bridge || bridge->vendor != PCI_VENDOR_ID_INTEL) + return; + + switch (bridge->device) { + case 0x1901: + dev->parent_d3cold = 1; + break; + } +} + static int nouveau_drm_probe(struct pci_dev *pdev, const struct pci_device_id *pent) { @@ -699,6 +753,7 @@ 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: @@ -735,6 +790,8 @@ nouveau_drm_remove(struct pci_dev *pdev) { struct drm_device *dev = pci_get_drvdata(pdev); + /* revert our workaround */ + pdev->parent_d3cold = false; nouveau_drm_device_remove(dev); pci_disable_device(pdev); } diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index d828ca835a98..9c4044fc2553 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -861,6 +861,14 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state) || (state == PCI_D2 && !dev->d2_support)) return -EIO; + /* + * Power management can be disabled for certain devices as they don't + * come back up later on runtime_resume. We rely on platform means to + * cut power consumption instead (e.g. ACPI). + */ + if (state != PCI_D0 && dev->parent_d3cold) + return 0; + pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr); if (pmcsr == (u16) ~0) { pci_err(dev, "can't change power state from %s to %s (config space inaccessible)\n", diff --git a/include/linux/pci.h b/include/linux/pci.h index 3840a541a9de..3c01f043519a 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -340,6 +340,7 @@ struct pci_dev { unsigned int no_d3cold:1; /* D3cold is forbidden */ unsigned int bridge_d3:1; /* Allow D3 for bridge */ unsigned int d3cold_allowed:1; /* D3cold is allowed by user */ + unsigned int parent_d3cold:1; /* Power manage the parent instead */ unsigned int mmio_always_on:1; /* Disallow turning off io/mem decoding during BAR sizing */ unsigned int wakeup_prepared:1;

[v7] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges

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