[PATCH 1/8] drm/panel: Add an API drm_panel_get_orientation() to return panel orientation

[Hsin-Yi Wang]

Panels usually call drm_connector_set_panel_orientation(), which is
later than drm/kms driver calling drm_dev_register(). This leads to a
WARN().

The orientation property is known earlier. For example, some panels
parse the property through device tree during probe.

Add an API to return the property from panel to drm/kms driver, so the
drivers are able to call drm_connector_set_panel_orientation() before
drm_dev_register().

Signed-off-by: Hsin-Yi Wang <hsinyi at chromium.org>
---
Previous discussion:
https://patchwork.kernel.org/project/linux-mediatek/cover/20220530081910.3947168-1-hsinyi@chromium.org/#24877477
---
 drivers/gpu/drm/drm_panel.c |  8 ++++++++
 include/drm/drm_panel.h     | 10 ++++++++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index f634371c717a..4a512ca80673 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -223,6 +223,14 @@ int drm_panel_get_modes(struct drm_panel *panel,
 }
 EXPORT_SYMBOL(drm_panel_get_modes);
 
+enum drm_panel_orientation drm_panel_get_orientation(struct drm_panel *panel)
+{
+	if (panel && panel->funcs && panel->funcs->get_orientation)
+		return panel->funcs->get_orientation(panel);
+
+	return DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
+}
+EXPORT_SYMBOL(drm_panel_get_orientation);
 #ifdef CONFIG_OF
 /**
  * of_drm_find_panel - look up a panel using a device tree node
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 1ba2d424a53f..d1bd3be4bbdf 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -133,6 +133,15 @@ struct drm_panel_funcs {
 	 * Allows panels to create panels-specific debugfs files.
 	 */
 	void (*debugfs_init)(struct drm_panel *panel, struct dentry *root);
+
+	/**
+	 * @get_orientation:
+	 *
+	 * Return the panel orientation set by device tree or EDID.
+	 *
+	 * This function is optional.
+	 */
+	enum drm_panel_orientation (*get_orientation)(struct drm_panel *panel);
 };
 
 /**
@@ -195,6 +204,7 @@ int drm_panel_enable(struct drm_panel *panel);
 int drm_panel_disable(struct drm_panel *panel);
 
 int drm_panel_get_modes(struct drm_panel *panel, struct drm_connector *connector);
+enum drm_panel_orientation drm_panel_get_orientation(struct drm_panel *panel);
 
 #if defined(CONFIG_OF) && defined(CONFIG_DRM_PANEL)
 struct drm_panel *of_drm_find_panel(const struct device_node *np);
-- 
2.36.1.255.ge46751e96f-goog