[Intel-gfx] [PATCH 3/6] drm/i915: fix FBC for cases where crtc->base.y is non-zero

[Paulo Zanoni]

From: Paulo Zanoni <paulo.r.zanoni at intel.com>

I only tested this on BDW, but since the register description is the
same ever since gen4, let's assume that all gens take the same
register format. If that's not true, then hopefully someone will
bisect a bug to this patch and we'll fix it.

Notice that the wrong fence offset register just means that the
hardware tracking will be wrong.

Testcases:
 - igt/kms_frontbuffer_tracking/fbc-1p-primscrn-pri-mfb-draw-mmap-gtt
 - igt/kms_frontbuffer_tracking/fbc-2p-primscrn-pri-mfb-draw-mmap-gtt

Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/intel_fbc.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 64f317a..0373cbc 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -64,6 +64,20 @@ static void i8xx_fbc_disable(struct drm_i915_private *dev_priv)
 	DRM_DEBUG_KMS("disabled FBC\n");
 }
 
+static unsigned int get_crtc_fence_y_offset(struct intel_crtc *crtc)
+{
+	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
+	struct drm_framebuffer *fb = crtc->base.primary->fb;
+	unsigned int tile_height;
+
+	tile_height = intel_tile_height(dev_priv->dev, fb->pixel_format,
+					fb->modifier[0]);
+
+	/* The value we want is the line number of the first tile that contains
+	 * the first vertical line of the CRTC. */
+	return crtc->base.y - (crtc->base.y % tile_height);
+}
+
 static void i8xx_fbc_enable(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = crtc->base.dev->dev_private;
@@ -97,7 +111,7 @@ static void i8xx_fbc_enable(struct intel_crtc *crtc)
 		fbc_ctl2 = FBC_CTL_FENCE_DBL | FBC_CTL_IDLE_IMM | FBC_CTL_CPU_FENCE;
 		fbc_ctl2 |= FBC_CTL_PLANE(crtc->plane);
 		I915_WRITE(FBC_CONTROL2, fbc_ctl2);
-		I915_WRITE(FBC_FENCE_OFF, crtc->base.y);
+		I915_WRITE(FBC_FENCE_OFF, get_crtc_fence_y_offset(crtc));
 	}
 
 	/* enable it... */
@@ -135,7 +149,7 @@ static void g4x_fbc_enable(struct intel_crtc *crtc)
 		dpfc_ctl |= DPFC_CTL_LIMIT_1X;
 	dpfc_ctl |= DPFC_CTL_FENCE_EN | obj->fence_reg;
 
-	I915_WRITE(DPFC_FENCE_YOFF, crtc->base.y);
+	I915_WRITE(DPFC_FENCE_YOFF, get_crtc_fence_y_offset(crtc));
 
 	/* enable it... */
 	I915_WRITE(DPFC_CONTROL, dpfc_ctl | DPFC_CTL_EN);
@@ -177,6 +191,7 @@ static void ilk_fbc_enable(struct intel_crtc *crtc)
 	struct drm_i915_gem_object *obj = intel_fb_obj(fb);
 	u32 dpfc_ctl;
 	int threshold = dev_priv->fbc.threshold;
+	unsigned int y_offset;
 
 	dev_priv->fbc.enabled = true;
 
@@ -200,7 +215,8 @@ static void ilk_fbc_enable(struct intel_crtc *crtc)
 	if (IS_GEN5(dev_priv))
 		dpfc_ctl |= obj->fence_reg;
 
-	I915_WRITE(ILK_DPFC_FENCE_YOFF, crtc->base.y);
+	y_offset = get_crtc_fence_y_offset(crtc);
+	I915_WRITE(ILK_DPFC_FENCE_YOFF, y_offset);
 	I915_WRITE(ILK_FBC_RT_BASE, i915_gem_obj_ggtt_offset(obj) | ILK_FBC_RT_VALID);
 	/* enable it... */
 	I915_WRITE(ILK_DPFC_CONTROL, dpfc_ctl | DPFC_CTL_EN);
@@ -208,7 +224,7 @@ static void ilk_fbc_enable(struct intel_crtc *crtc)
 	if (IS_GEN6(dev_priv)) {
 		I915_WRITE(SNB_DPFC_CTL_SA,
 			   SNB_CPU_FENCE_ENABLE | obj->fence_reg);
-		I915_WRITE(DPFC_CPU_FENCE_OFFSET, crtc->base.y);
+		I915_WRITE(DPFC_CPU_FENCE_OFFSET, y_offset);
 	}
 
 	intel_fbc_nuke(dev_priv);
@@ -288,7 +304,7 @@ static void gen7_fbc_enable(struct intel_crtc *crtc)
 
 	I915_WRITE(SNB_DPFC_CTL_SA,
 		   SNB_CPU_FENCE_ENABLE | obj->fence_reg);
-	I915_WRITE(DPFC_CPU_FENCE_OFFSET, crtc->base.y);
+	I915_WRITE(DPFC_CPU_FENCE_OFFSET, get_crtc_fence_y_offset(crtc));
 
 	intel_fbc_nuke(dev_priv);
 
-- 
2.1.4