[PATCH v4] 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>
---
v3->v4:
 * Add back in CONFIG_SUSPEND check
v2->v3:
 * Better direct users how to recover in the bad cases
v1->v2:
 * Only show messages in s2idle cases

 drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 21 +++++++++++++++------
 1 file changed, 15 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..2531da6cbec3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -1040,11 +1040,20 @@ 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;
-	}
-#endif
+#if IS_ENABLED(CONFIG_SUSPEND)
+	if (!(adev->flags & AMD_IS_APU) ||
+	    pm_suspend_target_state != PM_SUSPEND_TO_IDLE)
+		return false;
+#else
 	return false;
+#endif
+	if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
+		dev_warn_once(adev->dev,
+			      "Power consumption will be higher as BIOS has not been configured for suspend-to-idle.\n"
+			      "To use suspend-to-idle change the sleep mode in BIOS setup.\n");
+#if !IS_ENABLED(CONFIG_AMD_PMC)
+	dev_warn_once(adev->dev,
+		      "Power consumption will be higher as the kernel has not been compiled with CONFIG_AMD_PMC.\n");
+#endif
+	return true;
 }
-- 
2.25.1