[PATCH 15/23] drm/i915/guc: Provide register list to be saved/restored during engine reset

[Michel Thierry]

From: Arun Siluvery <arun.siluvery at linux.intel.com>

GuC expects a list of registers from the driver which are saved/restored
during engine reset. The type of value to be saved is controlled by
flags. We provide a minimal set of registers that we want GuC to save and
restore. This is not an issue in case of engine reset as driver initializes
most of them following an engine reset, but in case of media reset (aka
watchdog reset) which is completely internal to GuC (including resubmission
of hung workload), it is necessary to provide this list, otherwise GuC won't
be able to schedule further workloads after a reset. This is the minimal
set of registers identified for things to work as expected but if we see
any new issues, this register list can be expanded.

Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
Signed-off-by: Jeff McGee <jeff.mcgee at intel.com>
Signed-off-by: Michel Thierry <michel.thierry at intel.com>
---
 drivers/gpu/drm/i915/i915_guc_submission.c | 50 +++++++++++++++++++++++++++++-
 1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 1642fff9cf13..a8ad27b6b381 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -1003,6 +1003,22 @@ static void guc_policies_init(struct guc_policies *policies)
 	policies->is_valid = 1;
 }
 
+/*
+ * In this macro it is highly unlikely to exceed max value but even if we did
+ * it is not an error so just throw a warning and continue. Only side effect
+ * in continuing further means some registers won't be added to save/restore
+ * list.
+ */
+#define GUC_ADD_MMIO_REG_ADS(node, reg_addr, _flags)			\
+	do {								\
+		u32 __count = node->number_of_registers;		\
+		if (WARN_ON(__count >= GUC_REGSET_MAX_REGISTERS))	\
+			continue;					\
+		node->registers[__count].offset = reg_addr.reg;		\
+		node->registers[__count].flags = (_flags);		\
+		node->number_of_registers++;				\
+	} while (0)
+
 static int guc_ads_create(struct intel_guc *guc)
 {
 	struct drm_i915_private *dev_priv = guc_to_i915(guc);
@@ -1035,10 +1051,42 @@ static int guc_ads_create(struct intel_guc *guc)
 
 	/* MMIO reg state */
 	for_each_engine(engine, dev_priv, id) {
+		u32 flags;
+		struct guc_mmio_regset *eng_reg =
+			&blob->reg_state.engine_reg[engine->guc_id];
+
+		/*
+		 * Provide a list of registers to be saved/restored during gpu
+		 * reset. This is mainly required for Media reset (aka watchdog
+		 * timeout) which is completely under the control of GuC
+		 * (resubmission of hung workload is handled inside GuC).
+		 */
+		flags = GUC_REGSET_POWERCYCLE |
+			GUC_REGSET_ENGINERESET |
+			GUC_REGSET_SAVE_CURRENT_VALUE;
+
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_HEAD(engine->mmio_base),
+				     flags);
+
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_TAIL(engine->mmio_base),
+				     flags);
+
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_HWS_PGA(engine->mmio_base),
+				     flags);
+
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_MODE_GEN7(engine),
+				     (flags | GUC_REGSET_MASKED));
+
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_IMR(engine->mmio_base),
+				     flags);
+
+		DRM_DEBUG_DRIVER("%s register save/restore count: %u\n",
+				 engine->name, eng_reg->number_of_registers);
+
+		 /* Nothing to be white listed for now. */
 		blob->reg_state.white_list[engine->guc_id].mmio_start =
 			engine->mmio_base + GUC_MMIO_WHITE_LIST_START;
 
-		/* Nothing to be saved or restored for now. */
 		blob->reg_state.white_list[engine->guc_id].count = 0;
 	}
 
-- 
2.11.0