[PATCH 3/5] drm/panel: Add attach/detach callbacks

[Derek Basehore]

This adds the attach/detach callbacks. These are for setting up
internal state for the connector/panel pair that can't be done at
probe (since the connector doesn't exist) and which don't need to be
repeatedly done for every get/modes, prepare, or enable callback.
Values such as the panel orientation, and display size can be filled
in for the connector.

Signed-off-by: Derek Basehore <dbasehore at chromium.org>
---
 drivers/gpu/drm/drm_panel.c | 14 ++++++++++++++
 include/drm/drm_panel.h     |  4 ++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 3b689ce4a51a..72f67678d9d5 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -104,12 +104,23 @@ EXPORT_SYMBOL(drm_panel_remove);
  */
 int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector)
 {
+	int ret;
+
 	if (panel->connector)
 		return -EBUSY;
 
 	panel->connector = connector;
 	panel->drm = connector->dev;
 
+	if (panel->funcs->attach) {
+		ret = panel->funcs->attach(panel);
+		if (ret < 0) {
+			panel->connector = NULL;
+			panel->drm = NULL;
+			return ret;
+		}
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(drm_panel_attach);
@@ -128,6 +139,9 @@ EXPORT_SYMBOL(drm_panel_attach);
  */
 int drm_panel_detach(struct drm_panel *panel)
 {
+	if (panel->funcs->detach)
+		panel->funcs->detach(panel);
+
 	panel->connector = NULL;
 	panel->drm = NULL;
 
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 13631b2efbaa..e136e3a3c996 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -37,6 +37,8 @@ struct display_timing;
  * struct drm_panel_funcs - perform operations on a given panel
  * @disable: disable panel (turn off back light, etc.)
  * @unprepare: turn off panel
+ * @detach: detach panel->connector (clear internal state, etc.)
+ * @attach: attach panel->connector (update internal state, etc.)
  * @prepare: turn on panel and perform set up
  * @enable: enable panel (turn on back light, etc.)
  * @get_modes: add modes to the connector that the panel is attached to and
@@ -70,6 +72,8 @@ struct display_timing;
 struct drm_panel_funcs {
 	int (*disable)(struct drm_panel *panel);
 	int (*unprepare)(struct drm_panel *panel);
+	void (*detach)(struct drm_panel *panel);
+	int (*attach)(struct drm_panel *panel);
 	int (*prepare)(struct drm_panel *panel);
 	int (*enable)(struct drm_panel *panel);
 	int (*get_modes)(struct drm_panel *panel);
-- 
2.22.0.rc2.383.gf4fbbf30c2-goog