[PATCH 4.19 186/190] PCI: Reset both NVIDIA GPU and HDA in ThinkPad P50 workaround

From: Greg Kroah-Hartman
Date: Fri Sep 13 2019 - 09:20:42 EST

[ Upstream commit ad54567ad5d8e938ee6cf02e4f3867f18835ae6e ]

quirk_reset_lenovo_thinkpad_50_nvgpu() resets NVIDIA GPUs to work around
an apparent BIOS defect. It previously used pci_reset_function(), and
the available method was a bus reset, which was fine because there was
only one function on the bus. After b516ea586d71 ("PCI: Enable NVIDIA
HDA controllers"), there are now two functions (the HDA controller and
the GPU itself) on the bus, so the reset fails.

Use pci_reset_bus() explicitly instead of pci_reset_function() since it's
OK to reset both devices.

[bhelgaas: commit log, add e0547c81bfcf]
Fixes: b516ea586d71 ("PCI: Enable NVIDIA HDA controllers")
Fixes: e0547c81bfcf ("PCI: Reset Lenovo ThinkPad P50 nvgpu at boot if necessary")
Link: https://lore.kernel.org/r/20190801220117.14952-1-lyude@xxxxxxxxxx
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Lukas Wunner <lukas@xxxxxxxxx>
Cc: Daniel Drake <drake@xxxxxxxxxxxx>
Cc: Aaron Plattner <aplattner@xxxxxxxxxx>
Cc: Peter Wu <peter@xxxxxxxxxxxxx>
Cc: Ilia Mirkin <imirkin@xxxxxxxxxxxx>
Cc: Karol Herbst <kherbst@xxxxxxxxxx>
Cc: Maik Freudenberg <hhfeuer@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/pci/quirks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 311f8a33e62ff..06be52912dcdb 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5162,7 +5162,7 @@ static void quirk_reset_lenovo_thinkpad_p50_nvgpu(struct pci_dev *pdev)
if (ioread32(map + 0x2240c) & 0x2) {
pci_info(pdev, FW_BUG "GPU left initialized by EFI, resetting\n");
- ret = pci_reset_function(pdev);
+ ret = pci_reset_bus(pdev);
if (ret < 0)
pci_err(pdev, "Failed to reset GPU: %d\n", ret);