drm/i915: Debugfs support for GuC logging control

This patch provides debugfs interface i915_guc_output_control for
on the fly enabling/disabling of logging in GuC firmware and controlling
the verbosity level of logs.
The value written to the file, should have bit 0 set to enable logging and
bits 4-7 should contain the verbosity info.

v2: Add a forceful flush, to collect left over logs, on disabling logging.
    Useful for Validation.

v3: Besides minor cleanup, implement read method for the debugfs file and
    set the guc_log_level to -1 when logging is disabled. (Tvrtko)

v4: Minor cleanup & rebase. (Tvrtko)

v5:
- Lock struct_mutex after the NULL check for guc log buffer vma. (Chris)
- Rebase.

Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Akash Goel <akash.goel@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -2548,6 +2548,44 @@ static int i915_guc_log_dump(struct seq_file *m, void *data)
 	return 0;
 }
 
+static int i915_guc_log_control_get(void *data, u64 *val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+
+	if (!dev_priv->guc.log.vma)
+		return -EINVAL;
+
+	*val = i915.guc_log_level;
+
+	return 0;
+}
+
+static int i915_guc_log_control_set(void *data, u64 val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	int ret;
+
+	if (!dev_priv->guc.log.vma)
+		return -EINVAL;
+
+	ret = mutex_lock_interruptible(&dev->struct_mutex);
+	if (ret)
+		return ret;
+
+	intel_runtime_pm_get(dev_priv);
+	ret = i915_guc_log_control(dev_priv, val);
+	intel_runtime_pm_put(dev_priv);
+
+	mutex_unlock(&dev->struct_mutex);
+	return ret;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(i915_guc_log_control_fops,
+			i915_guc_log_control_get, i915_guc_log_control_set,
+			"%lld\n");
+
 static int i915_edp_psr_status(struct seq_file *m, void *data)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
@@ -5454,7 +5492,8 @@ static const struct i915_debugfs_files {
 	{"i915_fbc_false_color", &i915_fbc_fc_fops},
 	{"i915_dp_test_data", &i915_displayport_test_data_fops},
 	{"i915_dp_test_type", &i915_displayport_test_type_fops},
-	{"i915_dp_test_active", &i915_displayport_test_active_fops}
+	{"i915_dp_test_active", &i915_displayport_test_active_fops},
+	{"i915_guc_log_control", &i915_guc_log_control_fops}
 };
 
 void intel_display_crc_init(struct drm_i915_private *dev_priv)

drivers/gpu/drm/i915/i915_guc_submission.c

@@ -193,6 +193,16 @@ static int host2guc_force_logbuffer_flush(struct intel_guc *guc)
 	return host2guc_action(guc, data, 2);
 }
 
+static int host2guc_logging_control(struct intel_guc *guc, u32 control_val)
+{
+	u32 data[2];
+
+	data[0] = HOST2GUC_ACTION_UK_LOG_ENABLE_LOGGING;
+	data[1] = control_val;
+
+	return host2guc_action(guc, data, 2);
+}
+
 /*
  * Initialise, update, or clear doorbell data shared with the GuC
  *
@@ -1605,3 +1615,52 @@ void i915_guc_register(struct drm_i915_private *dev_priv)
 	guc_log_late_setup(&dev_priv->guc);
 	mutex_unlock(&dev_priv->drm.struct_mutex);
 }
+
+int i915_guc_log_control(struct drm_i915_private *dev_priv, u64 control_val)
+{
+	union guc_log_control log_param;
+	int ret;
+
+	log_param.value = control_val;
+
+	if (log_param.verbosity < GUC_LOG_VERBOSITY_MIN ||
+	    log_param.verbosity > GUC_LOG_VERBOSITY_MAX)
+		return -EINVAL;
+
+	/* This combination doesn't make sense & won't have any effect */
+	if (!log_param.logging_enabled && (i915.guc_log_level < 0))
+		return 0;
+
+	ret = host2guc_logging_control(&dev_priv->guc, log_param.value);
+	if (ret < 0) {
+		DRM_DEBUG_DRIVER("host2guc action failed %d\n", ret);
+		return ret;
+	}
+
+	i915.guc_log_level = log_param.verbosity;
+
+	/* If log_level was set as -1 at boot time, then the relay channel file
+	 * wouldn't have been created by now and interrupts also would not have
+	 * been enabled.
+	 */
+	if (!dev_priv->guc.log.relay_chan) {
+		ret = guc_log_late_setup(&dev_priv->guc);
+		if (!ret)
+			gen9_enable_guc_interrupts(dev_priv);
+	} else if (!log_param.logging_enabled) {
+		/* Once logging is disabled, GuC won't generate logs & send an
+		 * interrupt. But there could be some data in the log buffer
+		 * which is yet to be captured. So request GuC to update the log
+		 * buffer state and then collect the left over logs.
+		 */
+		i915_guc_flush_logs(dev_priv);
+
+		/* As logging is disabled, update log level to reflect that */
+		i915.guc_log_level = -1;
+	} else {
+		/* In case interrupts were disabled, enable them now */
+		gen9_enable_guc_interrupts(dev_priv);
+	}
+
+	return ret;
+}

drivers/gpu/drm/i915/intel_guc.h

@@ -188,5 +188,6 @@ void i915_guc_capture_logs(struct drm_i915_private *dev_priv);
 void i915_guc_flush_logs(struct drm_i915_private *dev_priv);
 void i915_guc_register(struct drm_i915_private *dev_priv);
 void i915_guc_unregister(struct drm_i915_private *dev_priv);
+int i915_guc_log_control(struct drm_i915_private *dev_priv, u64 control_val);
 
 #endif