diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8b781f8ad3a9..46ee0a90d558 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2135,6 +2135,7 @@ struct i915_params {
 	bool disable_display;
 	bool disable_vtd_wa;
 	int use_mmio_flip;
+	bool mmio_debug;
 };
 extern struct i915_params i915 __read_mostly;
 
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index bbdee21aec0e..62ee8308d682 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -49,6 +49,7 @@ struct i915_params i915 __read_mostly = {
 	.enable_cmd_parser = 1,
 	.disable_vtd_wa = 0,
 	.use_mmio_flip = 0,
+	.mmio_debug = 0,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -161,3 +162,8 @@ MODULE_PARM_DESC(enable_cmd_parser,
 module_param_named(use_mmio_flip, i915.use_mmio_flip, int, 0600);
 MODULE_PARM_DESC(use_mmio_flip,
 		 "use MMIO flips (-1=never, 0=driver discretion [default], 1=always)");
+
+module_param_named(mmio_debug, i915.mmio_debug, bool, 0600);
+MODULE_PARM_DESC(mmio_debug,
+	"Enable the MMIO debug code (default: false). This may negatively "
+	"affect performance.");
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index e0f0843569a6..6fee122eb252 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -514,20 +514,30 @@ ilk_dummy_write(struct drm_i915_private *dev_priv)
 }
 
 static void
-hsw_unclaimed_reg_clear(struct drm_i915_private *dev_priv, u32 reg)
+hsw_unclaimed_reg_debug(struct drm_i915_private *dev_priv, u32 reg, bool read,
+			bool before)
 {
+	const char *op = read ? "reading" : "writing to";
+	const char *when = before ? "before" : "after";
+
+	if (!i915.mmio_debug)
+		return;
+
 	if (__raw_i915_read32(dev_priv, FPGA_DBG) & FPGA_DBG_RM_NOCLAIM) {
-		DRM_ERROR("Unknown unclaimed register before writing to %x\n",
-			  reg);
+		WARN(1, "Unclaimed register detected %s %s register 0x%x\n",
+		     when, op, reg);
 		__raw_i915_write32(dev_priv, FPGA_DBG, FPGA_DBG_RM_NOCLAIM);
 	}
 }
 
 static void
-hsw_unclaimed_reg_check(struct drm_i915_private *dev_priv, u32 reg)
+hsw_unclaimed_reg_detect(struct drm_i915_private *dev_priv)
 {
+	if (i915.mmio_debug)
+		return;
+
 	if (__raw_i915_read32(dev_priv, FPGA_DBG) & FPGA_DBG_RM_NOCLAIM) {
-		DRM_ERROR("Unclaimed write to %x\n", reg);
+		DRM_ERROR("Unclaimed register detected. Please use the i915.mmio_debug=1 to debug this problem.");
 		__raw_i915_write32(dev_priv, FPGA_DBG, FPGA_DBG_RM_NOCLAIM);
 	}
 }
@@ -564,6 +574,7 @@ gen5_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
 static u##x \
 gen6_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
 	REG_READ_HEADER(x); \
+	hsw_unclaimed_reg_debug(dev_priv, reg, true, true); \
 	if (dev_priv->uncore.forcewake_count == 0 && \
 	    NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
 		dev_priv->uncore.funcs.force_wake_get(dev_priv, \
@@ -574,6 +585,7 @@ gen6_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
 	} else { \
 		val = __raw_i915_read##x(dev_priv, reg); \
 	} \
+	hsw_unclaimed_reg_debug(dev_priv, reg, true, false); \
 	REG_READ_FOOTER; \
 }
 
@@ -700,12 +712,13 @@ hsw_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, bool trace)
 	if (NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
 		__fifo_ret = __gen6_gt_wait_for_fifo(dev_priv); \
 	} \
-	hsw_unclaimed_reg_clear(dev_priv, reg); \
+	hsw_unclaimed_reg_debug(dev_priv, reg, false, true); \
 	__raw_i915_write##x(dev_priv, reg, val); \
 	if (unlikely(__fifo_ret)) { \
 		gen6_gt_check_fifodbg(dev_priv); \
 	} \
-	hsw_unclaimed_reg_check(dev_priv, reg); \
+	hsw_unclaimed_reg_debug(dev_priv, reg, false, false); \
+	hsw_unclaimed_reg_detect(dev_priv); \
 	REG_WRITE_FOOTER; \
 }