[Intel-xe] [PATCH v3 5/5] drm/xe/pm: Init pcode and restore vram on power lost

[Anshuman Gupta]

Don't init pcode and restore VRAM objects in vain.
We can rely on primary GT GUC_STATUS to detect whether
card has really lost power even when d3cold is allowed by xe.
Adding d3cold.lost_power flag to avoid pcode init and vram
restoration.
Also cleaning up the TODO code comment.

Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
---
 drivers/gpu/drm/xe/xe_device_types.h |  3 +++
 drivers/gpu/drm/xe/xe_guc.c          | 17 +++++++++++++++++
 drivers/gpu/drm/xe/xe_guc.h          |  1 +
 drivers/gpu/drm/xe/xe_pci.c          |  2 --
 drivers/gpu/drm/xe/xe_pm.c           | 15 ++++++++++++---
 5 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index c047571c8ab0..d9b6ef74d92c 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -336,6 +336,9 @@ struct xe_device {
 		/** @allowed: Indicates if d3cold is a valid device state */
 		bool allowed;
 
+		/** @power_lost Indicates if card has really lost power. */
+		bool power_lost;
+
 		/**
 		 * @vram_threshold is the permissible threshold(in megabytes)
 		 * for vram save/restore. d3cold will be disallowed,
diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
index 43f862aaacbe..3df48d91da0e 100644
--- a/drivers/gpu/drm/xe/xe_guc.c
+++ b/drivers/gpu/drm/xe/xe_guc.c
@@ -848,3 +848,20 @@ void xe_guc_print_info(struct xe_guc *guc, struct drm_printer *p)
 	xe_guc_ct_print(&guc->ct, p, false);
 	xe_guc_submit_print(guc, p);
 }
+
+/* Srtictly to called from RPM resume handler */
+bool xe_guc_has_lost_power(struct xe_guc *guc)
+{
+	struct xe_gt *gt = guc_to_gt(guc);
+	u32 status;
+	int err;
+
+	err = xe_force_wake_get(gt_to_fw(gt), XE_FW_GT);
+	if (err)
+		return false;
+
+	status = xe_mmio_read32(gt, GUC_STATUS);
+	xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
+
+	return  status & GS_MIA_IN_RESET;
+}
diff --git a/drivers/gpu/drm/xe/xe_guc.h b/drivers/gpu/drm/xe/xe_guc.h
index 74a74051f354..3e628bbbe69e 100644
--- a/drivers/gpu/drm/xe/xe_guc.h
+++ b/drivers/gpu/drm/xe/xe_guc.h
@@ -35,6 +35,7 @@ void xe_guc_reset_wait(struct xe_guc *guc);
 void xe_guc_stop_prepare(struct xe_guc *guc);
 int xe_guc_stop(struct xe_guc *guc);
 int xe_guc_start(struct xe_guc *guc);
+bool xe_guc_has_lost_power(struct xe_guc *guc);
 
 static inline u16 xe_engine_class_to_guc_class(enum xe_engine_class class)
 {
diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
index 78e906607188..8e10f4e019a1 100644
--- a/drivers/gpu/drm/xe/xe_pci.c
+++ b/drivers/gpu/drm/xe/xe_pci.c
@@ -829,8 +829,6 @@ static int xe_pci_runtime_idle(struct device *dev)
 		 * but maybe include some other conditions. So, before
 		 * we can re-enable the D3cold, we need to:
 		 * 1. rewrite the VRAM save / restore to avoid buffer object locks
-		 * 2. at resume, detect if we really lost power and avoid memory
-		 *    restoration if we were only up to d3cold
 		 */
 		xe->d3cold.allowed = false;
 	}
diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
index 4db4e5a1b051..83393f669c4c 100644
--- a/drivers/gpu/drm/xe/xe_pm.c
+++ b/drivers/gpu/drm/xe/xe_pm.c
@@ -16,6 +16,7 @@
 #include "xe_display.h"
 #include "xe_ggtt.h"
 #include "xe_gt.h"
+#include "xe_guc.h"
 #include "xe_irq.h"
 #include "xe_pcode.h"
 
@@ -192,11 +193,19 @@ int xe_pm_runtime_suspend(struct xe_device *xe)
 
 int xe_pm_runtime_resume(struct xe_device *xe)
 {
-	struct xe_gt *gt;
+	struct xe_gt *gt, *gt0;
 	u8 id;
 	int err;
 
-	if (xe->d3cold.allowed) {
+	/*
+	 * It can be possible that xe has allowed d3cold but other pcie devices
+	 * in gfx card soc would have blocked d3cold, therefore card has not
+	 * really lost power. Detecting primary Gt power is sufficient.
+	 */
+	gt0 = xe_device_get_gt(xe, 0);
+	xe->d3cold.power_lost = xe_guc_has_lost_power(&gt0->uc.guc);
+
+	if (xe->d3cold.allowed && xe->d3cold.power_lost) {
 		for_each_gt(gt, xe, id) {
 			err = xe_pcode_init(gt);
 			if (err)
@@ -217,7 +226,7 @@ int xe_pm_runtime_resume(struct xe_device *xe)
 	for_each_gt(gt, xe, id)
 		xe_gt_resume(gt);
 
-	if (xe->d3cold.allowed) {
+	if (xe->d3cold.allowed && xe->d3cold.power_lost) {
 		err = xe_bo_restore_user(xe);
 		if (err)
 			return err;
-- 
2.38.0