drm/i915/guc: Redefine guc_log_level modparam values

We used value -1 to indicate "disabled" and values 0..3 to
indicate "enabled", but most of our other modparams are using
-1 for "auto" mode and 0 for "disable". For consistency let's
change our log level values to:

-1: auto (depends on platform and Kconfig.debug settings)
 0: disabled
 1: enabled (severity level 0 = min)
 2: enabled (severity level 1)
 3: enabled (severity level 2)
 4: enabled (severity level 3 = max)

v2: fix commit message (Sagar)
    display sanitized modparam value (Sagar)
    unify sanitize messages (Sagar/Michal)

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180111152441.21676-1-michal.wajdeczko@intel.com
Reviewed-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_guc.c

@@ -215,6 +215,19 @@ static u32 get_core_family(struct drm_i915_private *dev_priv)
 	}
 }
 
+static u32 get_log_verbosity_flags(void)
+{
+	if (i915_modparams.guc_log_level > 0) {
+		u32 verbosity = i915_modparams.guc_log_level - 1;
+
+		GEM_BUG_ON(verbosity > GUC_LOG_VERBOSITY_MAX);
+		return verbosity << GUC_LOG_VERBOSITY_SHIFT;
+	}
+
+	GEM_BUG_ON(i915_modparams.enable_guc < 0);
+	return GUC_LOG_DISABLED;
+}
+
 /*
  * Initialise the GuC parameter block before starting the firmware
  * transfer. These parameters are read by the firmware on startup
@@ -247,12 +260,7 @@ void intel_guc_init_params(struct intel_guc *guc)
 
 	params[GUC_CTL_LOG_PARAMS] = guc->log.flags;
 
-	if (i915_modparams.guc_log_level >= 0) {
-		params[GUC_CTL_DEBUG] =
-			i915_modparams.guc_log_level << GUC_LOG_VERBOSITY_SHIFT;
-	} else {
-		params[GUC_CTL_DEBUG] = GUC_LOG_DISABLED;
-	}
+	params[GUC_CTL_DEBUG] = get_log_verbosity_flags();
 
 	/* If GuC submission is enabled, set up additional parameters here */
 	if (USES_GUC_SUBMISSION(dev_priv)) {
@@ -445,7 +453,7 @@ int intel_guc_resume(struct drm_i915_private *dev_priv)
 	if (guc->fw.load_status != INTEL_UC_FIRMWARE_SUCCESS)
 		return 0;
 
-	if (i915_modparams.guc_log_level >= 0)
+	if (i915_modparams.guc_log_level)
 		gen9_enable_guc_interrupts(dev_priv);
 
 	data[0] = INTEL_GUC_ACTION_EXIT_S_STATE;