drm/xe/pm: Init pcode and restore vram on power lost

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.

v2:
- %s/xe_guc_has_lost_power()/xe_guc_in_reset().
- Used existing gt instead of new variable. [Rodrigo]
- Added kernel-doc function comment. [Rodrigo]
- xe_guc_in_reset() return true if failed to get fw.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230718080703.239343-6-anshuman.gupta@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
index d44537abf7da..ed90d738d673 100644
--- a/drivers/gpu/drm/xe/xe_guc.c
+++ b/drivers/gpu/drm/xe/xe_guc.c
@@ -844,3 +844,30 @@ 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);
 }
+
+/**
+ * xe_guc_in_reset() - Detect if GuC MIA is in reset.
+ * @guc: The GuC object
+ *
+ * This function detects runtime resume from d3cold by leveraging
+ * GUC_STATUS, GUC doesn't get reset during d3hot,
+ * it strictly to be called from RPM resume handler.
+ *
+ * Return: true if failed to get forcewake or GuC MIA is in Reset,
+ * otherwise false.
+ */
+bool xe_guc_in_reset(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 true;
+
+	status = xe_mmio_read32(gt, GUC_STATUS);
+	xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
+
+	return  status & GS_MIA_IN_RESET;
+}