linux-kernel - [PATCH 5.16 019/164] drm/amd: Check if ASPM is enabled from PCIe subsystem

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Date:   Mon, 28 Feb 2022 18:23:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, koba.ko@...onical.com,
        Alex Deucher <alexander.deucher@....com>,
        Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH 5.16 019/164] drm/amd: Check if ASPM is enabled from PCIe subsystem

From: Mario Limonciello <mario.limonciello@....com>

commit 7294863a6f01248d72b61d38478978d638641bee upstream.

commit 0064b0ce85bb ("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: 0064b0ce85bb ("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@...onical.com
Reviewed-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Cc: stable@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -2014,6 +2014,9 @@ static int amdgpu_pci_probe(struct pci_d
 		return -ENODEV;
 	}
 
+	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;