drm/xe: Manually setup C6 when skip_guc_pc is set

Skip the init/start/stop GuC PC functions and toggle C6 using
register writes instead. Also request max possible frequency
as dynamic freq management is disabled.

v2: Fix compile warning

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/regs/xe_gt_regs.h

@@ -272,7 +272,11 @@
 #define   RPSWCTL_ENABLE			REG_FIELD_PREP(RPSWCTL_MASK, 2)
 #define   RPSWCTL_DISABLE			REG_FIELD_PREP(RPSWCTL_MASK, 0)
 #define RC_CONTROL				XE_REG(0xa090)
+#define   RC_CTL_HW_ENABLE			REG_BIT(31)
+#define   RC_CTL_TO_MODE			REG_BIT(28)
+#define   RC_CTL_RC6_ENABLE			REG_BIT(18)
 #define RC_STATE				XE_REG(0xa094)
+#define RC_IDLE_HYSTERSIS			XE_REG(0xa0ac)
 
 #define PMINTRMSK				XE_REG(0xa168)
 #define   PMINTR_DISABLE_REDIRECT_TO_GUC	REG_BIT(31)

drivers/gpu/drm/xe/xe_gt_idle.c

@@ -10,6 +10,8 @@
 #include "xe_gt_idle.h"
 #include "xe_gt_sysfs.h"
 #include "xe_guc_pc.h"
+#include "regs/xe_gt_regs.h"
+#include "xe_mmio.h"
 
 /**
  * DOC: Xe GT Idle
@@ -166,3 +168,25 @@ void xe_gt_idle_sysfs_init(struct xe_gt_idle *gtidle)
 		drm_warn(&xe->drm, "%s: drmm_add_action_or_reset failed, err: %d\n",
 			 __func__, err);
 }
+
+void xe_gt_idle_enable_c6(struct xe_gt *gt)
+{
+	xe_device_assert_mem_access(gt_to_xe(gt));
+	xe_force_wake_assert_held(gt_to_fw(gt), XE_FW_GT);
+
+	/* Units of 1280 ns for a total of 5s */
+	xe_mmio_write32(gt, RC_IDLE_HYSTERSIS, 0x3B9ACA);
+	/* Enable RC6 */
+	xe_mmio_write32(gt, RC_CONTROL,
+			RC_CTL_HW_ENABLE | RC_CTL_TO_MODE | RC_CTL_RC6_ENABLE);
+}
+
+void xe_gt_idle_disable_c6(struct xe_gt *gt)
+{
+	xe_device_assert_mem_access(gt_to_xe(gt));
+	xe_force_wake_assert_held(gt_to_fw(gt), XE_FORCEWAKE_ALL);
+
+	xe_mmio_write32(gt, PG_ENABLE, 0);
+	xe_mmio_write32(gt, RC_CONTROL, 0);
+	xe_mmio_write32(gt, RC_STATE, 0);
+}

drivers/gpu/drm/xe/xe_gt_idle.h

@@ -8,6 +8,10 @@
 
 #include "xe_gt_idle_types.h"
 
+struct xe_gt;
+
 void xe_gt_idle_sysfs_init(struct xe_gt_idle *gtidle);
+void xe_gt_idle_enable_c6(struct xe_gt *gt);
+void xe_gt_idle_disable_c6(struct xe_gt *gt);
 
 #endif /* _XE_GT_IDLE_H_ */

drivers/gpu/drm/xe/xe_guc_pc.c

@@ -16,6 +16,7 @@
 #include "xe_bo.h"
 #include "xe_device.h"
 #include "xe_gt.h"
+#include "xe_gt_idle.h"
 #include "xe_gt_sysfs.h"
 #include "xe_gt_types.h"
 #include "xe_guc_ct.h"
@@ -869,13 +870,24 @@ int xe_guc_pc_start(struct xe_guc_pc *pc)
 
 	xe_device_mem_access_get(pc_to_xe(pc));
 
-	memset(pc->bo->vmap.vaddr, 0, size);
-	slpc_shared_data_write(pc, header.size, size);
-
 	ret = xe_force_wake_get(gt_to_fw(gt), XE_FORCEWAKE_ALL);
 	if (ret)
 		goto out_fail_force_wake;
 
+	if (xe->info.skip_guc_pc) {
+		if (xe->info.platform != XE_PVC)
+			xe_gt_idle_enable_c6(gt);
+
+		/* Request max possible since dynamic freq mgmt is not enabled */
+		pc_set_cur_freq(pc, UINT_MAX);
+
+		ret = 0;
+		goto out;
+	}
+
+	memset(pc->bo->vmap.vaddr, 0, size);
+	slpc_shared_data_write(pc, header.size, size);
+
 	ret = pc_action_reset(pc);
 	if (ret)
 		goto out;
@@ -911,10 +923,17 @@ int xe_guc_pc_start(struct xe_guc_pc *pc)
  */
 int xe_guc_pc_stop(struct xe_guc_pc *pc)
 {
+	struct xe_device *xe = pc_to_xe(pc);
 	int ret;
 
 	xe_device_mem_access_get(pc_to_xe(pc));
 
+	if (xe->info.skip_guc_pc) {
+		xe_gt_idle_disable_c6(pc_to_gt(pc));
+		ret = 0;
+		goto out;
+	}
+
 	mutex_lock(&pc->freq_lock);
 	pc->freq_ready = false;
 	mutex_unlock(&pc->freq_lock);
@@ -935,6 +954,13 @@ int xe_guc_pc_stop(struct xe_guc_pc *pc)
 
 void xe_guc_pc_fini(struct xe_guc_pc *pc)
 {
+	struct xe_device *xe = pc_to_xe(pc);
+
+	if (xe->info.skip_guc_pc) {
+		xe_gt_idle_disable_c6(pc_to_gt(pc));
+		return;
+	}
+
 	XE_WARN_ON(xe_guc_pc_gucrc_disable(pc));
 	XE_WARN_ON(xe_guc_pc_stop(pc));
 	sysfs_remove_files(pc_to_gt(pc)->sysfs, pc_attrs);
@@ -955,6 +981,9 @@ int xe_guc_pc_init(struct xe_guc_pc *pc)
 	u32 size = PAGE_ALIGN(sizeof(struct slpc_shared_data));
 	int err;
 
+	if (xe->info.skip_guc_pc)
+		return 0;
+
 	mutex_init(&pc->freq_lock);
 
 	bo = xe_bo_create_pin_map(xe, tile, NULL, size,