drm/i915: Disable the mmio.debug WARN after it fires

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@intel.com>
Date:   Wed Jul 16 17:49:29 2014 -0300

    drm/i915: reorganize the unclaimed register detection code

v2: Automatically enable invalid mmio reporting for the *next* invalid
access if mmio_debug is disabled by default. This should give us clearer
debug information without polluting the logs too much.
v3: Compile fixes, rebase.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
[danvet: Update modparam text per the thread.]
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 e5516a3bb5cb0405a974a7dd1388347ac39e47d1..238bfd02b494d1debdb281da4d49eb727e51af96 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2442,7 +2442,7 @@ struct i915_params {
        bool disable_display;
        bool disable_vtd_wa;
        int use_mmio_flip;
-       bool mmio_debug;
+       int mmio_debug;
        bool verbose_state_checks;
        bool nuclear_pageflip;
 };

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 44f2262a555335ec6c0d6fe86e78537098ebc6ae..e2d20ffe65864bf5aed9c3d2ca24c69defb80571 100644 (file)
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -171,10 +171,10 @@ 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 for the first N failures (default: off). "
+       "This may negatively affect performance.");
 
 module_param_named(verbose_state_checks, i915.verbose_state_checks, bool, 0600);
 MODULE_PARM_DESC(verbose_state_checks,

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 4eb3cb2389b9749a344516ff7538d58703432ea3..ab5cc94588e10d1ac1ac81e3330073ea92d17ac7 100644 (file)
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -557,18 +557,24 @@ hsw_unclaimed_reg_debug(struct drm_i915_private *dev_priv, u32 reg, bool read,
                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--; /* Only report the first N failures */
        }
 }
 
 static void
 hsw_unclaimed_reg_detect(struct drm_i915_private *dev_priv)
 {
-       if (i915.mmio_debug)
+       static bool mmio_debug_once = true;
+
+       if (i915.mmio_debug || !mmio_debug_once)
                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.");
+               DRM_DEBUG("Unclaimed register detected, "
+                         "enabling oneshot unclaimed register reporting. "
+                         "Please use i915.mmio_debug=N for more information.\n");
                __raw_i915_write32(dev_priv, FPGA_DBG, FPGA_DBG_RM_NOCLAIM);
+               i915.mmio_debug = mmio_debug_once--;
        }
 }