[Intel-gfx] [PATCH v3] drm/i915: Fix FBC cfb stride programming for non X-tiled FB

[Praveen Paneri]

When FBC is enabled for linear, legacy Y-tiled and Yf-tiled
surfaces on gen9, the cfb stride must be programmed by SW as

cfb_stride = ceiling[(at least plane width in pixels)/
		     (32 * compression limit factor)] * 8

v2: Minor fix for a build error

v3: Fixed subject, register name and platform check (Ville)

Signed-off-by: Praveen Paneri <praveen.paneri at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h  | 3 +++
 drivers/gpu/drm/i915/intel_fbc.c | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 5d88c35..f4f0cb5 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6506,6 +6506,9 @@ enum {
 #define  GLK_CL1_PWR_DOWN	(1 << 11)
 #define  GLK_CL2_PWR_DOWN	(1 << 12)
 
+#define CHICKEN_MISC_4		_MMIO(0x4208c)
+#define   FBC_STRIDE_OVERRIDE	(1<<13)
+
 #define _CHICKEN_PIPESL_1_A	0x420b0
 #define _CHICKEN_PIPESL_1_B	0x420b4
 #define  HSW_FBCQ_DIS			(1 << 22)
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index ded2add..e7f259f 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -298,9 +298,17 @@ static bool ilk_fbc_is_active(struct drm_i915_private *dev_priv)
 static void gen7_fbc_activate(struct drm_i915_private *dev_priv)
 {
 	struct intel_fbc_reg_params *params = &dev_priv->fbc.params;
+	struct intel_fbc_state_cache *cache = &dev_priv->fbc.state_cache;
 	u32 dpfc_ctl;
 	int threshold = dev_priv->fbc.threshold;
 
+	if (IS_GEN9(dev_priv) &&
+	    i915_gem_object_get_tiling(cache->vma->obj) != I915_TILING_X) {
+		int cfb_stride = DIV_ROUND_UP(cache->plane.src_w,
+					      (32 * threshold)) * 8;
+		I915_WRITE(CHICKEN_MISC_4, FBC_STRIDE_OVERRIDE | cfb_stride);
+	}
+
 	dpfc_ctl = 0;
 	if (IS_IVYBRIDGE(dev_priv))
 		dpfc_ctl |= IVB_DPFC_CTL_PLANE(params->crtc.plane);
-- 
1.9.1