[PATCH] PCI: Extend D3hot delay for NVIDIA HDA controllers

[Alex Williamson <alex.williamson@redhat.com>]

Assignment of NVIDIA Ampere-based GPUs have seen a regression since the
below referenced commit, where the reduced D3hot transition delay appears
to introduce a small window where a D3hot->D0 transition followed by a bus
reset can wedge the device.  The entire device is subsequently unavailable,
returning -1 on config space read and is unrecoverable without a host reset.

This has been observed with RTX A2000 and A5000 GPU and audio functions
assigned to a Windows VM, where shutdown of the VM places the devices in
D3hot prior to vfio-pci performing a bus reset when userspace releases the
devices.  The issue has roughly a 2-3% chance of occurring per shutdown.

Restoring the HDA controller d3hot_delay to the effective value before the
below commit has been shown to resolve the issue.  NVIDIA confirms this
change should be safe for all of their HDA controllers.

Cc: Abhishek Sahu <abhsahu@nvidia.com>
Cc: Tarun Gupta <targupta@nvidia.com>
Fixes: 3e347969a577 ("PCI/PM: Reduce D3hot delay with usleep_range()")
Reported-by: Zhiyi Guo <zhguo@redhat.com>
Reviewed-by: Tarun Gupta <targupta@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

Unfortunately Tarun's reply with confirmation doesn't show up on lore,
possibly due to html email, or else I'd provide that as a Link:.

 drivers/pci/quirks.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 44cab813bf95..f4e2a88729fd 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -1939,6 +1939,19 @@ static void quirk_radeon_pm(struct pci_dev *dev)
 }
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x6741, quirk_radeon_pm);
 
+/*
+ * NVIDIA Ampere-based HDA controllers can wedge the whole device if a bus
+ * reset is performed too soon after transition to D0, extend d3hot_delay
+ * to previous effective default for all NVIDIA HDA controllers.
+ */
+static void quirk_nvidia_hda_pm(struct pci_dev *dev)
+{
+	quirk_d3hot_delay(dev, 20);
+}
+DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
+			      PCI_CLASS_MULTIMEDIA_HD_AUDIO, 8,
+			      quirk_nvidia_hda_pm);
+
 /*
  * Ryzen5/7 XHCI controllers fail upon resume from runtime suspend or s2idle.
  * https://bugzilla.kernel.org/show_bug.cgi?id=205587
-- 
2.39.2