[Intel-gfx] [PATCH] drm/i915: Disable the mmio.debug WARN after it fires

[Chris Wilson]

If we have a single unclaimed register, we will have lots. A WARN for
each one makes the machine unusable and does not aid debugging. Convert
the i915.mmio_debug option to a counter for how many WARNs to fire
before shutting up. Even when i915.mmio_debug was disabled it would
continue to shout an *ERROR* for every interrupt, without any
information at all for debugging.

The massive verbiage was added in
commit 5978118c39c2f72fd8b39ef9c086723542384809
Author: Paulo Zanoni <paulo.r.zanoni at intel.com>
Date:   Wed Jul 16 17:49:29 2014 -0300

    drm/i915: reorganize the unclaimed register detection code

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi at gmail.com>
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h     | 2 +-
 drivers/gpu/drm/i915/i915_params.c  | 5 ++---
 drivers/gpu/drm/i915/intel_uncore.c | 6 ++++--
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5448ce9d1490..314d8a60d55b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2310,7 +2310,7 @@ struct i915_params {
 	bool disable_display;
 	bool disable_vtd_wa;
 	int use_mmio_flip;
-	bool mmio_debug;
+	int 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 c91cb2033cc5..654a492fcfca 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -169,7 +169,6 @@ 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_param_named(mmio_debug, i915.mmio_debug, int, 0600);
 MODULE_PARM_DESC(mmio_debug,
-	"Enable the MMIO debug code (default: false). This may negatively "
-	"affect performance.");
+	"Enable the MMIO debug code. This may negatively affect performance.");
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index f0230b0e8e11..b830407dc2aa 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -714,25 +714,27 @@ hsw_unclaimed_reg_debug(struct drm_i915_private *dev_priv, u32 reg, bool read,
 	const char *op = read ? "reading" : "writing to";
 	const char *when = before ? "before" : "after";
 
-	if (!i915.mmio_debug)
+	if (i915.mmio_debug <= 0)
 		return;
 
 	if (__raw_i915_read32(dev_priv, FPGA_DBG) & FPGA_DBG_RM_NOCLAIM) {
 		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);
+		i915.mmio_debug--;
 	}
 }
 
 static void
 hsw_unclaimed_reg_detect(struct drm_i915_private *dev_priv)
 {
-	if (i915.mmio_debug)
+	if (i915.mmio_debug > 0)
 		return;
 
 	if (__raw_i915_read32(dev_priv, FPGA_DBG) & FPGA_DBG_RM_NOCLAIM) {
 		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);
+		i915.mmio_debug--;
 	}
 }
 
-- 
2.1.3