[Intel-gfx] [PATCH v6 13/20] 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.

v2: REGSET_MASKED is too difficult for GuC, use REGSET_SAVE_DEFAULT_VALUE
and current value from RING_MODE reg instead; no need to preserve
head/tail either, be extra paranoid and save whitelisted registers (Daniele).

Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
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 | 60 +++++++++++++++++++++++++++++-
 1 file changed, 58 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 1ea36a88d2fb..d772718861df 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -1003,6 +1003,24 @@ 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, defvalue)		\
+	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);		\
+		if (defvalue)						\
+			node->registers[__count].value = (defvalue);	\
+		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);
@@ -1016,6 +1034,7 @@ static int guc_ads_create(struct intel_guc *guc)
 		u8 reg_state_buffer[GUC_S3_SAVE_SPACE_PAGES * PAGE_SIZE];
 	} __packed *blob;
 	struct intel_engine_cs *engine;
+	struct i915_workarounds *workarounds = &dev_priv->workarounds;
 	enum intel_engine_id id;
 	u32 base;
 
@@ -1035,6 +1054,39 @@ static int guc_ads_create(struct intel_guc *guc)
 
 	/* MMIO reg state */
 	for_each_engine(engine, dev_priv, id) {
+		u32 i;
+		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).
+		 */
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_HWS_PGA(engine->mmio_base),
+				     GUC_REGSET_ENGINERESET |
+				     GUC_REGSET_SAVE_CURRENT_VALUE, 0);
+
+		/*
+		 * Workaround the guc issue with masked registers, note that
+		 * at this point guc submission is still disabled and the mode
+		 * register doesnt have the irq_steering bit set, which we
+		 * need to fwd irqs to GuC.
+		 */
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_MODE_GEN7(engine),
+				     GUC_REGSET_ENGINERESET |
+				     GUC_REGSET_SAVE_DEFAULT_VALUE,
+				     I915_READ(RING_MODE_GEN7(engine)) |
+				     GFX_INTERRUPT_STEERING | (0xFFFF<<16));
+
+		GUC_ADD_MMIO_REG_ADS(eng_reg, RING_IMR(engine->mmio_base),
+				     GUC_REGSET_ENGINERESET |
+				     GUC_REGSET_SAVE_CURRENT_VALUE, 0);
+
+		DRM_DEBUG_DRIVER("%s register save/restore count: %u\n",
+				 engine->name, eng_reg->number_of_registers);
+
 		blob->reg_state.white_list[engine->guc_id].mmio_start =
 			i915_mmio_reg_offset(RING_FORCE_TO_NONPRIV(engine->mmio_base, 0));
 
@@ -1044,9 +1096,13 @@ static int guc_ads_create(struct intel_guc *guc)
 		 * inconsistencies with the handling of FORCE_TO_NONPRIV
 		 * registers.
 		 */
-		blob->reg_state.white_list[engine->guc_id].count = 0;
+		blob->reg_state.white_list[engine->guc_id].count =
+					workarounds->hw_whitelist_count[id];
 
-		/* Nothing to be saved or restored for now. */
+		for (i = 0; i < workarounds->hw_whitelist_count[id]; i++) {
+			blob->reg_state.white_list[engine->guc_id].offsets[i] =
+				I915_READ(RING_FORCE_TO_NONPRIV(engine->mmio_base, i));
+		}
 	}
 
 	/*
-- 
2.11.0