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Bug#884061: #884061: linux-image-4.9.0-4-amd64: screen scrolls wildly



Control: tags 884061 +patch

On 2017-12-12, Nick Smallbone wrote:
> I get this too after upgrading from 4.9.30-2+deb9u5 to 4.9.65-3.
> Same dmesg error as Vagrant, together with either crazy flickering
> or a hard crash. It happens usually about 30 seconds after starting X.
>
> I tried using "git bisect" on the upstream linux-stable repository.
> It points the finger at the following commit:
>
>   7de694782cbe7840f2c0de6f1e70f41fc1b8b6e8 is the first bad commit
>   commit 7de694782cbe7840f2c0de6f1e70f41fc1b8b6e8
>   Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>   Date:   Thu Oct 19 17:13:40 2017 +0200
>   
>       drm/i915: Do not rely on wm preservation for ILK watermarks
>       
>       commit 8777b927b92cf5b6c29f9f9d3c737addea9ac8a7 upstream.

Thanks for bisecting the issue!

I just tested simply reverting this patch with 4.9.65-3+deb9u1, and it's
been running without problem for at least three hours. So that confirms
that it works around the issue, at least.

I'm not sure if there's a better fix than simply reverting this; this is
clearly a regression for at least two users that makes the system almost
unusable.


From 4c01095ae53794023e772f9afb753bef67c3d84c Mon Sep 17 00:00:00 2001
From: Vagrant Cascadian <vagrant@debian.org>
Date: Thu, 28 Dec 2017 11:21:30 -0800
Subject: [PATCH] Revert "drm/i915: Do not rely on wm preservation for ILK
 watermarks"

This reverts commit 7de694782cbe7840f2c0de6f1e70f41fc1b8b6e8.
---
 drivers/gpu/drm/i915/intel_drv.h |  1 +
 drivers/gpu/drm/i915/intel_pm.c  | 52 +++++++++++++++++++++++-----------------
 2 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 3ce9ba30d827..a19ec06f9e42 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -457,6 +457,7 @@ struct intel_crtc_scaler_state {
 
 struct intel_pipe_wm {
 	struct intel_wm_level wm[5];
+	struct intel_wm_level raw_wm[5];
 	uint32_t linetime;
 	bool fbc_wm_enabled;
 	bool pipe_enabled;
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 277a8026460b..49de4760cc16 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -27,7 +27,6 @@
 
 #include <linux/cpufreq.h>
 #include <drm/drm_plane_helper.h>
-#include <drm/drm_atomic_helper.h>
 #include "i915_drv.h"
 #include "intel_drv.h"
 #include "../../../platform/x86/intel_ips.h"
@@ -2018,9 +2017,9 @@ static void ilk_compute_wm_level(const struct drm_i915_private *dev_priv,
 				 const struct intel_crtc *intel_crtc,
 				 int level,
 				 struct intel_crtc_state *cstate,
-				 const struct intel_plane_state *pristate,
-				 const struct intel_plane_state *sprstate,
-				 const struct intel_plane_state *curstate,
+				 struct intel_plane_state *pristate,
+				 struct intel_plane_state *sprstate,
+				 struct intel_plane_state *curstate,
 				 struct intel_wm_level *result)
 {
 	uint16_t pri_latency = dev_priv->wm.pri_latency[level];
@@ -2342,24 +2341,28 @@ static int ilk_compute_pipe_wm(struct intel_crtc_state *cstate)
 	struct intel_pipe_wm *pipe_wm;
 	struct drm_device *dev = state->dev;
 	const struct drm_i915_private *dev_priv = to_i915(dev);
-	struct drm_plane *plane;
-	const struct drm_plane_state *plane_state;
-	const struct intel_plane_state *pristate = NULL;
-	const struct intel_plane_state *sprstate = NULL;
-	const struct intel_plane_state *curstate = NULL;
+	struct intel_plane *intel_plane;
+	struct intel_plane_state *pristate = NULL;
+	struct intel_plane_state *sprstate = NULL;
+	struct intel_plane_state *curstate = NULL;
 	int level, max_level = ilk_wm_max_level(dev), usable_level;
 	struct ilk_wm_maximums max;
 
 	pipe_wm = &cstate->wm.ilk.optimal;
 
-	drm_atomic_crtc_state_for_each_plane_state(plane, plane_state, &cstate->base) {
-		const struct intel_plane_state *ps = to_intel_plane_state(plane_state);
+	for_each_intel_plane_on_crtc(dev, intel_crtc, intel_plane) {
+		struct intel_plane_state *ps;
 
-		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
+		ps = intel_atomic_get_existing_plane_state(state,
+							   intel_plane);
+		if (!ps)
+			continue;
+
+		if (intel_plane->base.type == DRM_PLANE_TYPE_PRIMARY)
 			pristate = ps;
-		else if (plane->type == DRM_PLANE_TYPE_OVERLAY)
+		else if (intel_plane->base.type == DRM_PLANE_TYPE_OVERLAY)
 			sprstate = ps;
-		else if (plane->type == DRM_PLANE_TYPE_CURSOR)
+		else if (intel_plane->base.type == DRM_PLANE_TYPE_CURSOR)
 			curstate = ps;
 	}
 
@@ -2381,9 +2384,11 @@ static int ilk_compute_pipe_wm(struct intel_crtc_state *cstate)
 	if (pipe_wm->sprites_scaled)
 		usable_level = 0;
 
-	memset(&pipe_wm->wm, 0, sizeof(pipe_wm->wm));
 	ilk_compute_wm_level(dev_priv, intel_crtc, 0, cstate,
-			     pristate, sprstate, curstate, &pipe_wm->wm[0]);
+			     pristate, sprstate, curstate, &pipe_wm->raw_wm[0]);
+
+	memset(&pipe_wm->wm, 0, sizeof(pipe_wm->wm));
+	pipe_wm->wm[0] = pipe_wm->raw_wm[0];
 
 	if (IS_HASWELL(dev) || IS_BROADWELL(dev))
 		pipe_wm->linetime = hsw_compute_linetime_wm(cstate);
@@ -2393,8 +2398,8 @@ static int ilk_compute_pipe_wm(struct intel_crtc_state *cstate)
 
 	ilk_compute_wm_reg_maximums(dev, 1, &max);
 
-	for (level = 1; level <= usable_level; level++) {
-		struct intel_wm_level *wm = &pipe_wm->wm[level];
+	for (level = 1; level <= max_level; level++) {
+		struct intel_wm_level *wm = &pipe_wm->raw_wm[level];
 
 		ilk_compute_wm_level(dev_priv, intel_crtc, level, cstate,
 				     pristate, sprstate, curstate, wm);
@@ -2404,10 +2409,13 @@ static int ilk_compute_pipe_wm(struct intel_crtc_state *cstate)
 		 * register maximums since such watermarks are
 		 * always invalid.
 		 */
-		if (!ilk_validate_wm_level(level, &max, wm)) {
-			memset(wm, 0, sizeof(*wm));
-			break;
-		}
+		if (level > usable_level)
+			continue;
+
+		if (ilk_validate_wm_level(level, &max, wm))
+			pipe_wm->wm[level] = *wm;
+		else
+			usable_level = level;
 	}
 
 	return 0;
-- 
2.11.0



live well,
  vagrant

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