openwrt/target/linux/bcm27xx/patches-6.1/950-0955-drm-vc4-Enable-SCALER_CONTROL-early-in-HVS-init.patch

From 542ba979b4fa1e07ff2ad2dabbdc12e92b80ed46 Mon Sep 17 00:00:00 2001
From: Tim Gover <tim.gover@raspberrypi.com>
Date: Thu, 13 Jul 2023 17:47:22 +0100
Subject: [PATCH] drm/vc4: Enable SCALER_CONTROL early in HVS init

Always enable SCALER_CONTROL before attempting other HVS
operations. It's safe to write to some parts of the HVS but
in general it's dangerous to do this because it can cause bus
lockups.

Signed-off-by: Tim Gover <tim.gover@raspberrypi.com>
---
 drivers/gpu/drm/vc4/vc4_hvs.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -1303,6 +1303,10 @@ static int vc4_hvs_hw_init(struct vc4_hv
 	struct vc4_dev *vc4 = hvs->vc4;
 	u32 dispctrl, reg;
 
+	dispctrl = HVS_READ(SCALER_DISPCTRL);
+	dispctrl |= SCALER_DISPCTRL_ENABLE;
+	HVS_WRITE(SCALER_DISPCTRL, dispctrl);
+
 	reg = HVS_READ(SCALER_DISPECTRL);
 	reg &= ~SCALER_DISPECTRL_DSP2_MUX_MASK;
 	HVS_WRITE(SCALER_DISPECTRL,
@@ -1324,8 +1328,6 @@ static int vc4_hvs_hw_init(struct vc4_hv
 		  reg | VC4_SET_FIELD(3, SCALER_DISPDITHER_DSP5_MUX));
 
 	dispctrl = HVS_READ(SCALER_DISPCTRL);
-
-	dispctrl |= SCALER_DISPCTRL_ENABLE;
 	dispctrl |= SCALER_DISPCTRL_DISPEIRQ(0) |
 		    SCALER_DISPCTRL_DISPEIRQ(1) |
 		    SCALER_DISPCTRL_DISPEIRQ(2);
@@ -1521,6 +1523,10 @@ static int vc4_hvs_bind(struct device *d
 	else
 		hvs->dlist = hvs->regs + SCALER5_DLIST_START;
 
+	ret = vc4_hvs_hw_init(hvs);
+	if (ret)
+		return ret;
+
 	/* Upload filter kernels.  We only have the one for now, so we
 	 * keep it around for the lifetime of the driver.
 	 */
@@ -1530,10 +1536,6 @@ static int vc4_hvs_bind(struct device *d
 	if (ret)
 		return ret;
 
-	ret = vc4_hvs_hw_init(hvs);
-	if (ret)
-		return ret;
-
 	ret = vc4_hvs_cob_init(hvs);
 	if (ret)
 		return ret;