[PATCH] drm/amdgpu: skip the noirq suspend reset for a switcheroo-parked GPU

[Theo Andersen Carton <andersen.theo@gmail.com>]

amdgpu_pmops_suspend_noirq() resets the ASIC unconditionally. When the GPU
has been parked by vga_switcheroo it has neither power nor a PCIe link, so
the reset cannot reach it: pci_set_power_state() reports the device as
inaccessible and amdgpu_asic_reset() returns -EINVAL. A failure there
aborts the entire noirq suspend phase, and with it the system suspend, so
the machine cannot sleep at all while the GPU is switched off.

amdgpu_device_prepare(), amdgpu_device_suspend() and amdgpu_device_resume()
all bail out early on DRM_SWITCH_POWER_OFF. This callback was added later,
for an unrelated reason, and did not inherit the check. nouveau guards
every one of its PM callbacks the same way.

Bail out the same way here. On a single-GPU system switch_power_state is
never DRM_SWITCH_POWER_OFF, so this is a no-op there.

Found on a MacBookPro11,5, where the Radeon is powered down through
apple-gmux so that the internal panel can be driven by the iGPU instead.
Every suspend failed in amdgpu_pmops_suspend_noirq() while the card was
off; with this check a full S3 cycle completes.

Fixes: 9e051720f9d3 ("drm/amdgpu: Ensure HDA function is suspended before ASIC reset")
Cc: stable@vger.kernel.org
Signed-off-by: Theo Andersen Carton <andersen.theo@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 5c33c19fd9bc..d9d794a7db96 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -2664,6 +2664,14 @@ static int amdgpu_pmops_suspend_noirq(struct device *dev)
 	struct amdgpu_device *adev = drm_to_adev(drm_dev);
 	int r;
 
+	/*
+	 * A GPU parked by vga_switcheroo has no power and no PCIe link, so the
+	 * ASIC reset below would fail and abort the whole noirq suspend phase.
+	 * Bail out like amdgpu_device_prepare/suspend/resume() already do.
+	 */
+	if (drm_dev->switch_power_state == DRM_SWITCH_POWER_OFF)
+		return 0;
+
 	if (amdgpu_acpi_should_gpu_reset(adev)) {
 		amdgpu_device_lock_reset_domain(adev->reset_domain);
 		r = amdgpu_asic_reset(adev);

base-commit: 50d05c7c76c96b90462f24debacca971d2e86713
-- 
2.55.0