drm/i915: Unset cursor if out-of-bounds upon mode change (v4)

The docs warn that to position the cursor such that no part of it is
visible on the pipe is an undefined operation. Avoid such circumstances
upon changing the mode, or at any other time, by unsetting the cursor if
it moves out of bounds.

"For normal high resolution display modes, the cursor must have at least a
single pixel positioned over the active screen.” (p143, p148 of the hardware
registers docs).

Fixes:

  Bug 24748 - [965G] Graphics crashes when resolution is changed with KMS
              enabled
  https://bugs.freedesktop.org/show_bug.cgi?id=24748

v2: Only update the cursor registers if they change.
v3: Fix the unsigned comparision of x,y against width,height.
v4: Always set CUR.BASE or else the cursor may become corrupt.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: Christian Eggers <ceggers@gmx.de>
Cc: Christopher James Halse Rogers  <chalserogers@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/intel_display.c

@@ -43,6 +43,7 @@
 bool intel_pipe_has_type (struct drm_crtc *crtc, int type);
 static void intel_update_watermarks(struct drm_device *dev);
 static void intel_increase_pllclock(struct drm_crtc *crtc, bool schedule);
+static void intel_crtc_update_cursor(struct drm_crtc *crtc);
 
 typedef struct {
     /* given values */
@@ -3575,6 +3576,9 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 		return -EINVAL;
 	}
 
+	/* Ensure that the cursor is valid for the new mode before changing... */
+	intel_crtc_update_cursor(crtc);
+
 	if (is_lvds && dev_priv->lvds_downclock_avail) {
 		has_reduced_clock = limit->find_pll(limit, crtc,
 							    dev_priv->lvds_downclock,
@@ -4111,6 +4115,85 @@ void intel_crtc_load_lut(struct drm_crtc *crtc)
 	}
 }
 
+/* If no-part of the cursor is visible on the framebuffer, then the GPU may hang... */
+static void intel_crtc_update_cursor(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	int pipe = intel_crtc->pipe;
+	int x = intel_crtc->cursor_x;
+	int y = intel_crtc->cursor_y;
+	uint32_t base, pos;
+	bool visible;
+
+	pos = 0;
+
+	if (crtc->fb) {
+		base = intel_crtc->cursor_addr;
+		if (x > (int) crtc->fb->width)
+			base = 0;
+
+		if (y > (int) crtc->fb->height)
+			base = 0;
+	} else
+		base = 0;
+
+	if (x < 0) {
+		if (x + intel_crtc->cursor_width < 0)
+			base = 0;
+
+		pos |= CURSOR_POS_SIGN << CURSOR_X_SHIFT;
+		x = -x;
+	}
+	pos |= x << CURSOR_X_SHIFT;
+
+	if (y < 0) {
+		if (y + intel_crtc->cursor_height < 0)
+			base = 0;
+
+		pos |= CURSOR_POS_SIGN << CURSOR_Y_SHIFT;
+		y = -y;
+	}
+	pos |= y << CURSOR_Y_SHIFT;
+
+	visible = base != 0;
+	if (!visible && !intel_crtc->cursor_visble)
+		return;
+
+	I915_WRITE(pipe == 0 ? CURAPOS : CURBPOS, pos);
+	if (intel_crtc->cursor_visble != visible) {
+		uint32_t cntl = I915_READ(pipe == 0 ? CURACNTR : CURBCNTR);
+		if (base) {
+			/* Hooray for CUR*CNTR differences */
+			if (IS_MOBILE(dev) || IS_I9XX(dev)) {
+				cntl &= ~(CURSOR_MODE | MCURSOR_PIPE_SELECT);
+				cntl |= CURSOR_MODE_64_ARGB_AX | MCURSOR_GAMMA_ENABLE;
+				cntl |= pipe << 28; /* Connect to correct pipe */
+			} else {
+				cntl &= ~(CURSOR_FORMAT_MASK);
+				cntl |= CURSOR_ENABLE;
+				cntl |= CURSOR_FORMAT_ARGB | CURSOR_GAMMA_ENABLE;
+			}
+		} else {
+			if (IS_MOBILE(dev) || IS_I9XX(dev)) {
+				cntl &= ~(CURSOR_MODE | MCURSOR_GAMMA_ENABLE);
+				cntl |= CURSOR_MODE_DISABLE;
+			} else {
+				cntl &= ~(CURSOR_ENABLE | CURSOR_GAMMA_ENABLE);
+			}
+		}
+		I915_WRITE(pipe == 0 ? CURACNTR : CURBCNTR, cntl);
+
+		intel_crtc->cursor_visble = visible;
+	}
+	/* and commit changes on next vblank */
+	I915_WRITE(pipe == 0 ? CURABASE : CURBBASE, base);
+
+	if (visible)
+		intel_mark_busy(dev, to_intel_framebuffer(crtc->fb)->obj);
+}
+
 static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 				 struct drm_file *file_priv,
 				 uint32_t handle,
@@ -4121,11 +4204,7 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct drm_gem_object *bo;
 	struct drm_i915_gem_object *obj_priv;
-	int pipe = intel_crtc->pipe;
-	uint32_t control = (pipe == 0) ? CURACNTR : CURBCNTR;
-	uint32_t base = (pipe == 0) ? CURABASE : CURBBASE;
-	uint32_t temp = I915_READ(control);
-	size_t addr;
+	uint32_t addr;
 	int ret;
 
 	DRM_DEBUG_KMS("\n");
@@ -4133,12 +4212,6 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 	/* if we want to turn off the cursor ignore width and height */
 	if (!handle) {
 		DRM_DEBUG_KMS("cursor off\n");
-		if (IS_MOBILE(dev) || IS_I9XX(dev)) {
-			temp &= ~(CURSOR_MODE | MCURSOR_GAMMA_ENABLE);
-			temp |= CURSOR_MODE_DISABLE;
-		} else {
-			temp &= ~(CURSOR_ENABLE | CURSOR_GAMMA_ENABLE);
-		}
 		addr = 0;
 		bo = NULL;
 		mutex_lock(&dev->struct_mutex);
@@ -4180,7 +4253,8 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 
 		addr = obj_priv->gtt_offset;
 	} else {
-		ret = i915_gem_attach_phys_object(dev, bo, (pipe == 0) ? I915_GEM_PHYS_CURSOR_0 : I915_GEM_PHYS_CURSOR_1);
+		ret = i915_gem_attach_phys_object(dev, bo,
+						  (intel_crtc->pipe == 0) ? I915_GEM_PHYS_CURSOR_0 : I915_GEM_PHYS_CURSOR_1);
 		if (ret) {
 			DRM_ERROR("failed to attach phys object\n");
 			goto fail_locked;
@@ -4191,21 +4265,7 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 	if (!IS_I9XX(dev))
 		I915_WRITE(CURSIZE, (height << 12) | width);
 
-	/* Hooray for CUR*CNTR differences */
-	if (IS_MOBILE(dev) || IS_I9XX(dev)) {
-		temp &= ~(CURSOR_MODE | MCURSOR_PIPE_SELECT);
-		temp |= CURSOR_MODE_64_ARGB_AX | MCURSOR_GAMMA_ENABLE;
-		temp |= (pipe << 28); /* Connect to correct pipe */
-	} else {
-		temp &= ~(CURSOR_FORMAT_MASK);
-		temp |= CURSOR_ENABLE;
-		temp |= CURSOR_FORMAT_ARGB | CURSOR_GAMMA_ENABLE;
-	}
-
  finish:
-	I915_WRITE(control, temp);
-	I915_WRITE(base, addr);
-
 	if (intel_crtc->cursor_bo) {
 		if (dev_priv->info->cursor_needs_physical) {
 			if (intel_crtc->cursor_bo != bo)
@@ -4219,6 +4279,10 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 
 	intel_crtc->cursor_addr = addr;
 	intel_crtc->cursor_bo = bo;
+	intel_crtc->cursor_width = width;
+	intel_crtc->cursor_height = height;
+
+	intel_crtc_update_cursor(crtc);
 
 	return 0;
 fail_unpin:
@@ -4232,34 +4296,12 @@ static int intel_crtc_cursor_set(struct drm_crtc *crtc,
 
 static int intel_crtc_cursor_move(struct drm_crtc *crtc, int x, int y)
 {
-	struct drm_device *dev = crtc->dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
-	struct intel_framebuffer *intel_fb;
-	int pipe = intel_crtc->pipe;
-	uint32_t temp = 0;
-	uint32_t adder;
-
-	if (crtc->fb) {
-		intel_fb = to_intel_framebuffer(crtc->fb);
-		intel_mark_busy(dev, intel_fb->obj);
-	}
-
-	if (x < 0) {
-		temp |= CURSOR_POS_SIGN << CURSOR_X_SHIFT;
-		x = -x;
-	}
-	if (y < 0) {
-		temp |= CURSOR_POS_SIGN << CURSOR_Y_SHIFT;
-		y = -y;
-	}
 
-	temp |= x << CURSOR_X_SHIFT;
-	temp |= y << CURSOR_Y_SHIFT;
+	intel_crtc->cursor_x = x;
+	intel_crtc->cursor_y = y;
 
-	adder = intel_crtc->cursor_addr;
-	I915_WRITE((pipe == 0) ? CURAPOS : CURBPOS, temp);
-	I915_WRITE((pipe == 0) ? CURABASE : CURBBASE, adder);
+	intel_crtc_update_cursor(crtc);
 
 	return 0;
 }

drivers/gpu/drm/i915/intel_drv.h

@@ -143,8 +143,6 @@ struct intel_crtc {
 	struct drm_crtc base;
 	enum pipe pipe;
 	enum plane plane;
-	struct drm_gem_object *cursor_bo;
-	uint32_t cursor_addr;
 	u8 lut_r[256], lut_g[256], lut_b[256];
 	int dpms_mode;
 	bool busy; /* is scanout buffer being updated frequently? */
@@ -153,6 +151,12 @@ struct intel_crtc {
 	struct intel_overlay *overlay;
 	struct intel_unpin_work *unpin_work;
 	int fdi_lanes;
+
+	struct drm_gem_object *cursor_bo;
+	uint32_t cursor_addr;
+	int16_t cursor_x, cursor_y;
+	int16_t cursor_width, cursor_height;
+	bool cursor_visble;
 };
 
 #define to_intel_crtc(x) container_of(x, struct intel_crtc, base)