drm/i915/fbc: Pass i915 instead of FBC instance to FBC underrun stuff

The underrun code doesn't need to know any details about FBC, so
just pass in the whole device rather than a specific FBC instance.
We could make this a bit more fine grained by also passing in the
pipe to intel_fbc_handle_fifo_underrun_irq() and letting the FBC
code figure which FBC instance (if any) is active on said pipe.
But that seems a bit overkill for this so don't bother.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211124113652.22090-11-ville.syrjala@linux.intel.comReviewed-by: Mika Kahola <mika.kahola@intel.com>

drivers/gpu/drm/i915/display/intel_display_debugfs.c

@@ -2044,9 +2044,7 @@ i915_fifo_underrun_reset_write(struct file *filp,
 			return ret;
 	}
 
-	ret = intel_fbc_reset_underrun(&dev_priv->fbc);
-	if (ret)
-		return ret;
+	intel_fbc_reset_underrun(dev_priv);
 
 	return cnt;
 }

drivers/gpu/drm/i915/display/intel_fbc.c

@@ -1547,21 +1547,21 @@ static void intel_fbc_underrun_work_fn(struct work_struct *work)
 
 /*
  * intel_fbc_reset_underrun - reset FBC fifo underrun status.
- * @fbc: The FBC instance
+ * @i915: the i915 device
  *
  * See intel_fbc_handle_fifo_underrun_irq(). For automated testing we
  * want to re-enable FBC after an underrun to increase test coverage.
  */
-int intel_fbc_reset_underrun(struct intel_fbc *fbc)
+void intel_fbc_reset_underrun(struct drm_i915_private *i915)
 {
-	struct drm_i915_private *i915 = fbc->i915;
-	int ret;
+	struct intel_fbc *fbc = &i915->fbc;
+
+	if (!HAS_FBC(i915))
+		return;
 
 	cancel_work_sync(&fbc->underrun_work);
 
-	ret = mutex_lock_interruptible(&fbc->lock);
-	if (ret)
-		return ret;
+	mutex_lock(&fbc->lock);
 
 	if (fbc->underrun_detected) {
 		drm_dbg_kms(&i915->drm,
@@ -1571,13 +1571,11 @@ int intel_fbc_reset_underrun(struct intel_fbc *fbc)
 
 	fbc->underrun_detected = false;
 	mutex_unlock(&fbc->lock);
-
-	return 0;
 }
 
 /**
  * intel_fbc_handle_fifo_underrun_irq - disable FBC when we get a FIFO underrun
- * @fbc: The FBC instance
+ * @i915: i915 device
  *
  * Without FBC, most underruns are harmless and don't really cause too many
  * problems, except for an annoying message on dmesg. With FBC, underruns can
@@ -1589,9 +1587,11 @@ int intel_fbc_reset_underrun(struct intel_fbc *fbc)
  *
  * This function is called from the IRQ handler.
  */
-void intel_fbc_handle_fifo_underrun_irq(struct intel_fbc *fbc)
+void intel_fbc_handle_fifo_underrun_irq(struct drm_i915_private *i915)
 {
-	if (!HAS_FBC(fbc->i915))
+	struct intel_fbc *fbc = &i915->fbc;
+
+	if (!HAS_FBC(i915))
 		return;
 
 	/* There's no guarantee that underrun_detected won't be set to true

drivers/gpu/drm/i915/display/intel_fbc.h

@@ -35,8 +35,8 @@ void intel_fbc_invalidate(struct drm_i915_private *dev_priv,
 			  enum fb_op_origin origin);
 void intel_fbc_flush(struct drm_i915_private *dev_priv,
 		     unsigned int frontbuffer_bits, enum fb_op_origin origin);
-void intel_fbc_handle_fifo_underrun_irq(struct intel_fbc *fbc);
-int intel_fbc_reset_underrun(struct intel_fbc *fbc);
+void intel_fbc_handle_fifo_underrun_irq(struct drm_i915_private *i915);
+void intel_fbc_reset_underrun(struct drm_i915_private *i915);
 int intel_fbc_set_false_color(struct intel_fbc *fbc, bool enable);
 
 #endif /* __INTEL_FBC_H__ */

drivers/gpu/drm/i915/display/intel_fifo_underrun.c

@@ -434,7 +434,7 @@ void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
 			drm_err(&dev_priv->drm, "CPU pipe %c FIFO underrun\n", pipe_name(pipe));
 	}
 
-	intel_fbc_handle_fifo_underrun_irq(&dev_priv->fbc);
+	intel_fbc_handle_fifo_underrun_irq(dev_priv);
 }
 
 /**