950-0441-drm-vc4-Increase-the-core-clock-based-on-HVS-load.patch

From 7971426f2462b02ea1bf12d902ca066e07eeb64b Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Wed, 26 May 2021 16:13:02 +0200
Subject: [PATCH] drm/vc4: Increase the core clock based on HVS load

Depending on a given HVS output (HVS to PixelValves) and input (planes
attached to a channel) load, the HVS needs for the core clock to be
raised above its boot time default.

Failing to do so will result in a vblank timeout and a stalled display
pipeline.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_drv.h |  1 +
 drivers/gpu/drm/vc4/vc4_kms.c | 13 +++++++++++++
 2 files changed, 14 insertions(+)

--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -321,6 +321,7 @@ struct vc4_hvs {
 	u32 __iomem *dlist;
 
 	struct clk *core_clk;
+	struct clk_request *core_req;
 
 	/* Memory manager for CRTCs to allocate space in the display
 	 * list.  Units are dwords.
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -391,6 +391,11 @@ static void vc4_atomic_commit_tail(struc
 						new_hvs_state->core_clock_rate);
 
 		core_req = clk_request_start(hvs->core_clk, core_rate);
+		/*
+		 * And remove the previous one based on the HVS
+		 * requirements if any.
+		 */
+               clk_request_done(hvs->core_req);
 	}
 
 	drm_atomic_helper_commit_modeset_disables(dev, state);
@@ -418,6 +423,14 @@ static void vc4_atomic_commit_tail(struc
 		drm_dbg(dev, "Running the core clock at %lu Hz\n",
 			new_hvs_state->core_clock_rate);
 
+		/*
+		 * Request a clock rate based on the current HVS
+		 * requirements.
+		 */
+		hvs->core_req = clk_request_start(hvs->core_clk,
+						  new_hvs_state->core_clock_rate);
+
+		/* And drop the temporary request */
 		clk_request_done(core_req);
 	}
 }