[Intel-gfx] [PATCHv4 1/3] drm/i915: Make finding unused crtc as a generic function

[Durgadoss R]

Looping over the crtc list and finding an unused crtc
has other users like upfront link training. Hence move it to
a common function to re-use the logic.

v4:
* Added ERR_PTR as a return value in kernel Doc comment (Ander)
v3:
* Added kernel Doc and removed an invalid comment (Ander)
* Rebased on top of latest code which includes locking
  for state->enable usage.
v2:
* Made this as a separate function instead of having it
  inside upfront link train code.

Signed-off-by: Durgadoss R <durgadoss.r at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 74 +++++++++++++++++++++---------------
 drivers/gpu/drm/i915/intel_drv.h     |  2 +
 2 files changed, 45 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4cca155..a6df48b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10404,6 +10404,43 @@ static int intel_modeset_setup_plane_state(struct drm_atomic_state *state,
 	return 0;
 }
 
+/**
+ * intel_get_unused_crtc - Find an unused crtc for the given encoder
+ * @encoder: drm_encoder structure
+ * @ctx: ctx pointer to use with locking
+ *
+ * This function tries to find an unused crtc that can drive
+ * the given encoder. Returns NULL or ERR_PTR on failure.
+ */
+struct drm_crtc *intel_get_unused_crtc(struct drm_encoder *encoder,
+				struct drm_modeset_acquire_ctx *ctx)
+{
+	struct drm_crtc *possible_crtc;
+	struct drm_crtc *crtc = NULL;
+	struct drm_device *dev = encoder->dev;
+	int ret, i = -1;
+
+	for_each_crtc(dev, possible_crtc) {
+		i++;
+		if (!(encoder->possible_crtcs & (1 << i)))
+			continue;
+
+		ret = drm_modeset_lock(&possible_crtc->mutex, ctx);
+		if (ret)
+			return ERR_PTR(ret);
+
+		if (possible_crtc->state->enable) {
+			drm_modeset_unlock(&possible_crtc->mutex);
+			continue;
+		}
+
+		crtc = possible_crtc;
+		break;
+	}
+
+	return crtc;
+}
+
 bool intel_get_load_detect_pipe(struct drm_connector *connector,
 				struct drm_display_mode *mode,
 				struct intel_load_detect_pipe *old,
@@ -10412,7 +10449,6 @@ bool intel_get_load_detect_pipe(struct drm_connector *connector,
 	struct intel_crtc *intel_crtc;
 	struct intel_encoder *intel_encoder =
 		intel_attached_encoder(connector);
-	struct drm_crtc *possible_crtc;
 	struct drm_encoder *encoder = &intel_encoder->base;
 	struct drm_crtc *crtc = NULL;
 	struct drm_device *dev = encoder->dev;
@@ -10421,7 +10457,7 @@ bool intel_get_load_detect_pipe(struct drm_connector *connector,
 	struct drm_atomic_state *state = NULL, *restore_state = NULL;
 	struct drm_connector_state *connector_state;
 	struct intel_crtc_state *crtc_state;
-	int ret, i = -1;
+	int ret;
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s], [ENCODER:%d:%s]\n",
 		      connector->base.id, connector->name,
@@ -10451,39 +10487,15 @@ retry:
 		ret = drm_modeset_lock(&crtc->mutex, ctx);
 		if (ret)
 			goto fail;
-
-		/* Make sure the crtc and connector are running */
-		goto found;
-	}
-
-	/* Find an unused one (if possible) */
-	for_each_crtc(dev, possible_crtc) {
-		i++;
-		if (!(encoder->possible_crtcs & (1 << i)))
-			continue;
-
-		ret = drm_modeset_lock(&possible_crtc->mutex, ctx);
-		if (ret)
+	} else {
+		crtc = intel_get_unused_crtc(encoder, ctx);
+		if (IS_ERR_OR_NULL(crtc)) {
+			ret = PTR_ERR_OR_ZERO(crtc);
+			DRM_DEBUG_KMS("no pipe available for load-detect\n");
 			goto fail;
-
-		if (possible_crtc->state->enable) {
-			drm_modeset_unlock(&possible_crtc->mutex);
-			continue;
 		}
-
-		crtc = possible_crtc;
-		break;
-	}
-
-	/*
-	 * If we didn't find an unused CRTC, don't use any.
-	 */
-	if (!crtc) {
-		DRM_DEBUG_KMS("no pipe available for load-detect\n");
-		goto fail;
 	}
 
-found:
 	intel_crtc = to_intel_crtc(crtc);
 
 	ret = drm_modeset_lock(&crtc->primary->mutex, ctx);
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index e13ce22..27b5dcd 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1159,6 +1159,8 @@ bool intel_get_load_detect_pipe(struct drm_connector *connector,
 void intel_release_load_detect_pipe(struct drm_connector *connector,
 				    struct intel_load_detect_pipe *old,
 				    struct drm_modeset_acquire_ctx *ctx);
+struct drm_crtc *intel_get_unused_crtc(struct drm_encoder *encoder,
+				struct drm_modeset_acquire_ctx *ctx);
 int intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
 			       unsigned int rotation);
 struct drm_framebuffer *
-- 
1.9.1