[PATCH v6 2/4] 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>
---
v5->v6:
 * Make CONFIG_SUSPEND wrap around entire function to make more readable
 * Return false if system not properly configured (relevant with later patch)
 drivers/gpu/drm/amd/amdgpu/amdgpu.h      |  8 ++++++--
 drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 24 +++++++++++++++++++-----
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 3bc76759c143..b1db703753f2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1409,12 +1409,10 @@ int amdgpu_acpi_smart_shift_update(struct drm_device *dev, enum amdgpu_ss ss_sta
 int amdgpu_acpi_pcie_notify_device_ready(struct amdgpu_device *adev);
 
 void amdgpu_acpi_get_backlight_caps(struct amdgpu_dm_backlight_caps *caps);
-bool amdgpu_acpi_is_s0ix_active(struct amdgpu_device *adev);
 void amdgpu_acpi_detect(void);
 #else
 static inline int amdgpu_acpi_init(struct amdgpu_device *adev) { return 0; }
 static inline void amdgpu_acpi_fini(struct amdgpu_device *adev) { }
-static inline bool amdgpu_acpi_is_s0ix_active(struct amdgpu_device *adev) { return false; }
 static inline void amdgpu_acpi_detect(void) { }
 static inline bool amdgpu_acpi_is_power_shift_control_supported(void) { return false; }
 static inline int amdgpu_acpi_power_shift_control(struct amdgpu_device *adev,
@@ -1423,6 +1421,12 @@ static inline int amdgpu_acpi_smart_shift_update(struct drm_device *dev,
 						 enum amdgpu_ss ss_state) { return 0; }
 #endif
 
+#if defined(CONFIG_ACPI) && defined(CONFIG_SUSPEND)
+bool amdgpu_acpi_is_s0ix_active(struct amdgpu_device *adev);
+#else
+static inline bool amdgpu_acpi_is_s0ix_active(struct amdgpu_device *adev) { return false; }
+#endif
+
 int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,
 			   uint64_t addr, struct amdgpu_bo **bo,
 			   struct amdgpu_bo_va_mapping **mapping);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
index 4811b0faafd9..b19d40751802 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -1031,6 +1031,7 @@ void amdgpu_acpi_detect(void)
 	}
 }
 
+#if IS_ENABLED(CONFIG_SUSPEND)
 /**
  * amdgpu_acpi_is_s0ix_active
  *
@@ -1040,11 +1041,24 @@ 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,
+			      "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");
+		return false;
 	}
-#endif
+
+#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");
 	return false;
+#else
+	return true;
+#endif /* CONFIG_AMD_PMC */
 }
+
+#endif /* CONFIG_SUSPEND */
-- 
2.25.1