UBUNTU: SAUCE: drm/amd: Check if ASPM is enabled from PCIe subsystem

BugLink: https://bugs.launchpad.net/bugs/1961855

commit 0064b0c ("drm/amd/pm: enable ASPM by default") enabled ASPM
by default but a variety of hardware configurations it turns out that this
caused a regression.

* PPC64LE hardware does not support ASPM at a hardware level.
  CONFIG_PCIEASPM is often disabled on these architectures.
* Some dGPUs on ALD platforms don't work with ASPM enabled and PCIe
  subsystem disables it

Check with the PCIe subsystem to see that ASPM has been enabled
or not.

Fixes: 0064b0c ("drm/amd/pm: enable ASPM by default")
Link: https://wiki.raptorcs.com/w/images/a/ad/P9_PHB_version1.0_27July2018_pub.pdf
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1723
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1739
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1885
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1907
Tested-by: koba.ko@canonical.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Ref: https://patchwork.freedesktop.org/patch/474615/
Signed-off-by: Koba Ko <koba.ko@canonical.com>
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -1259,6 +1259,9 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
 	bool is_fw_fb;
 	resource_size_t base, size;
 
+	if (amdgpu_aspm == -1 && !pcie_aspm_enabled(pdev))
+		amdgpu_aspm = 0;
+
 	if (!amdgpu_virtual_display &&
 	    amdgpu_device_asic_has_dc_support(flags & AMD_ASIC_MASK))
 		supports_atomic = true;