[PATCH 2/2] drm/xe/lnl: Enable GuC SLPC DCC task

[Rodrigo Vivi]

Enable DCC (Duty Cycle Control) in Lunar Lake.

DCC is the SLPC task that tries to keep
the GT from operating inefficiently when thermally constrained.

Although the recommendation is to enable it, LNL GuC is leaving
it disabled by default on LNL.

It would minimize the GT frequency oscillation on throttled
scenarios, which could potentially reduce latencies.

v2: Move set_policies call after wait for running state, so
    we ensure it is not overwritten. (Vinay)
v3: Fix English in the commit message (Jonathan)

Cc: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 drivers/gpu/drm/xe/xe_guc_pc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
index 5080cbea3790..1ee826049b93 100644
--- a/drivers/gpu/drm/xe/xe_guc_pc.c
+++ b/drivers/gpu/drm/xe/xe_guc_pc.c
@@ -956,6 +956,16 @@ static int pc_init_freqs(struct xe_guc_pc *pc)
 	return ret;
 }
 
+static int slpc_set_policies(struct xe_guc_pc *pc)
+{
+	struct xe_device *xe = pc_to_xe(pc);
+
+	if (xe->info.platform == XE_LUNARLAKE)
+		return pc_action_set_param(pc, SLPC_PARAM_TASK_ENABLE_DCC, 1);
+
+	return 0;
+}
+
 /**
  * xe_guc_pc_start - Start GuC's Power Conservation component
  * @pc: Xe_GuC_PC instance
@@ -1000,6 +1010,10 @@ int xe_guc_pc_start(struct xe_guc_pc *pc)
 		goto out;
 	}
 
+	ret = slpc_set_policies(pc);
+	if (ret)
+		goto out;
+
 	ret = pc_init_freqs(pc);
 	if (ret)
 		goto out;
-- 
2.47.1