[PATCH v2] drm/amd: Warn users about potential s0ix problems

[Mario Limonciello]

On some OEM setups users can configure the BIOS for S3 or S2idle.
When configured to S3 users can still choose 's2idle' in the kernel by
using `/sys/power/mem_sleep`.  Before commit 6dc8265f9803 ("drm/amdgpu:
always reset the asic in suspend (v2)"), the GPU would crash.  Now when
configured this way, the system should resume but will use more power.

As such, adjust the `amdpu_acpi_is_s0ix function` to warn users about
potential power consumption issues during their first attempt at
suspending.

Reported-by: Bjoren Dasse <bjoern.daase at gmail.com>
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1824
Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
---
v1->v2:
 * Only show messages in s2idle cases
 drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
index 4811b0faafd9..1295de6d6c30 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -1040,11 +1040,15 @@ void amdgpu_acpi_detect(void)
  */
 bool amdgpu_acpi_is_s0ix_active(struct amdgpu_device *adev)
 {
-#if IS_ENABLED(CONFIG_AMD_PMC) && IS_ENABLED(CONFIG_SUSPEND)
-	if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0) {
-		if (adev->flags & AMD_IS_APU)
-			return pm_suspend_target_state == PM_SUSPEND_TO_IDLE;
-	}
+	if (!(adev->flags & AMD_IS_APU) ||
+	    pm_suspend_target_state != PM_SUSPEND_TO_IDLE)
+		return false;
+	if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
+		dev_warn_once(adev->dev,
+			      "BIOS is not configured for suspend-to-idle, power consumption will be higher\n");
+#if !IS_ENABLED(CONFIG_AMD_PMC)
+	dev_warn_once(adev->dev,
+		      "amd-pmc is not enabled in the kernel, power consumption will be higher\n");
 #endif
-	return false;
+	return true;
 }
-- 
2.25.1