From: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date: Mon, 14 Sep 2015 18:19:56 +0000 (-0300)
Subject: drm/i915: check for the supported strides on HSW+ FBC
X-Git-Tag: KARO-TX6UL-2015-11-03~85^2~15^2~32
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=adf70c65cff66d843d66469dbe13ef1ed21e062b;p=karo-tx-linux.git

drm/i915: check for the supported strides on HSW+ FBC

Don't allow FBC for cases where the spec says we can't FBC.

v2:
  - Just WARN_ON() the strides that should have been caught earlier
    (Daniel)
  - Make it a new function since I expect this to grow more.
v3:
  - Document which IGT test is exercised by this.
v4:
  - Implement the restrictions for gens 2-6 too (Ville).
  - Fix off-by-one mistake (Ville).

Testcase: igt/kms_frontbuffer_tracking/fbc-badstride
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7cbc81f718a7..d4240dba16ff 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -948,6 +948,7 @@ struct i915_fbc {
 		FBC_CHIP_DEFAULT, /* disabled by default on this chip */
 		FBC_ROTATION, /* rotation is not supported */
 		FBC_IN_DBG_MASTER, /* kernel debugger is active */
+		FBC_BAD_STRIDE, /* stride is not supported */
 	} no_fbc_reason;
 
 	bool (*fbc_enabled)(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index 9e42079e1705..db3809134a29 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -480,6 +480,8 @@ const char *intel_no_fbc_reason_str(enum no_fbc_reason reason)
 		return "rotation unsupported";
 	case FBC_IN_DBG_MASTER:
 		return "Kernel debugger is active";
+	case FBC_BAD_STRIDE:
+		return "framebuffer stride not supported";
 	default:
 		MISSING_CASE(reason);
 		return "unknown reason";
@@ -671,6 +673,27 @@ static int intel_fbc_setup_cfb(struct drm_i915_private *dev_priv, int size,
 	return intel_fbc_alloc_cfb(dev_priv, size, fb_cpp);
 }
 
+static bool stride_is_valid(struct drm_i915_private *dev_priv,
+			    unsigned int stride)
+{
+	/* These should have been caught earlier. */
+	WARN_ON(stride < 512);
+	WARN_ON((stride & (64 - 1)) != 0);
+
+	/* Below are the additional FBC restrictions. */
+
+	if (IS_GEN2(dev_priv) || IS_GEN3(dev_priv))
+		return stride == 4096 || stride == 8192;
+
+	if (IS_GEN4(dev_priv) && !IS_G4X(dev_priv) && stride < 2048)
+		return false;
+
+	if (stride > 16384)
+		return false;
+
+	return true;
+}
+
 /**
  * __intel_fbc_update - enable/disable FBC as needed, unlocked
  * @dev_priv: i915 device instance
@@ -781,6 +804,11 @@ static void __intel_fbc_update(struct drm_i915_private *dev_priv)
 		goto out_disable;
 	}
 
+	if (!stride_is_valid(dev_priv, fb->pitches[0])) {
+		set_no_fbc_reason(dev_priv, FBC_BAD_STRIDE);
+		goto out_disable;
+	}
+
 	/* If the kernel debugger is active, always disable compression */
 	if (in_dbg_master()) {
 		set_no_fbc_reason(dev_priv, FBC_IN_DBG_MASTER);