drm: Add atomic variants for bridge enable/disable

This patch adds atomic variants for all of
pre_enable/enable/disable/post_disable bridge functions. These will be
called from the appropriate atomic helper functions. If the bridge
driver doesn't implement the atomic version of the function, we will
fall back to the vanilla implementation.

Note that some drivers call drm_bridge_disable directly, and these cases
are not covered. It's up to the driver to decide whether to implement
both atomic_disable and disable, or if it's not necessary.

Changes in v3:
- Added to the patchset
Changes in v4:
- Fix up docbook references (Daniel)
Changes in v5:
- None

Link to v3: https://patchwork.freedesktop.org/patch/msgid/20190502194956.218441-4-sean@poorly.run
Link to v4: https://patchwork.freedesktop.org/patch/msgid/20190508160920.144739-4-sean@poorly.run

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190611160844.257498-4-sean@poorly.run

drivers/gpu/drm/drm_bridge.c

@@ -352,6 +352,116 @@ void drm_bridge_enable(struct drm_bridge *bridge)
 }
 EXPORT_SYMBOL(drm_bridge_enable);
 
+/**
+ * drm_atomic_bridge_disable - disables all bridges in the encoder chain
+ * @bridge: bridge control structure
+ * @state: atomic state being committed
+ *
+ * Calls &drm_bridge_funcs.atomic_disable (falls back on
+ * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
+ * starting from the last bridge to the first. These are called before calling
+ * &drm_encoder_helper_funcs.atomic_disable
+ *
+ * Note: the bridge passed should be the one closest to the encoder
+ */
+void drm_atomic_bridge_disable(struct drm_bridge *bridge,
+			       struct drm_atomic_state *state)
+{
+	if (!bridge)
+		return;
+
+	drm_atomic_bridge_disable(bridge->next, state);
+
+	if (bridge->funcs->atomic_disable)
+		bridge->funcs->atomic_disable(bridge, state);
+	else if (bridge->funcs->disable)
+		bridge->funcs->disable(bridge);
+}
+EXPORT_SYMBOL(drm_atomic_bridge_disable);
+
+/**
+ * drm_atomic_bridge_post_disable - cleans up after disabling all bridges in the
+ *				    encoder chain
+ * @bridge: bridge control structure
+ * @state: atomic state being committed
+ *
+ * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
+ * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
+ * starting from the first bridge to the last. These are called after completing
+ * &drm_encoder_helper_funcs.atomic_disable
+ *
+ * Note: the bridge passed should be the one closest to the encoder
+ */
+void drm_atomic_bridge_post_disable(struct drm_bridge *bridge,
+				    struct drm_atomic_state *state)
+{
+	if (!bridge)
+		return;
+
+	if (bridge->funcs->atomic_post_disable)
+		bridge->funcs->atomic_post_disable(bridge, state);
+	else if (bridge->funcs->post_disable)
+		bridge->funcs->post_disable(bridge);
+
+	drm_atomic_bridge_post_disable(bridge->next, state);
+}
+EXPORT_SYMBOL(drm_atomic_bridge_post_disable);
+
+/**
+ * drm_atomic_bridge_pre_enable - prepares for enabling all bridges in the
+ *				  encoder chain
+ * @bridge: bridge control structure
+ * @state: atomic state being committed
+ *
+ * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
+ * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
+ * starting from the last bridge to the first. These are called before calling
+ * &drm_encoder_helper_funcs.atomic_enable
+ *
+ * Note: the bridge passed should be the one closest to the encoder
+ */
+void drm_atomic_bridge_pre_enable(struct drm_bridge *bridge,
+				  struct drm_atomic_state *state)
+{
+	if (!bridge)
+		return;
+
+	drm_atomic_bridge_pre_enable(bridge->next, state);
+
+	if (bridge->funcs->atomic_pre_enable)
+		bridge->funcs->atomic_pre_enable(bridge, state);
+	else if (bridge->funcs->pre_enable)
+		bridge->funcs->pre_enable(bridge);
+}
+EXPORT_SYMBOL(drm_atomic_bridge_pre_enable);
+
+/**
+ * drm_atomic_bridge_enable - enables all bridges in the encoder chain
+ * @bridge: bridge control structure
+ * @state: atomic state being committed
+ *
+ * Calls &drm_bridge_funcs.atomic_enable (falls back on
+ * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
+ * starting from the first bridge to the last. These are called after completing
+ * &drm_encoder_helper_funcs.atomic_enable
+ *
+ * Note: the bridge passed should be the one closest to the encoder
+ */
+void drm_atomic_bridge_enable(struct drm_bridge *bridge,
+			      struct drm_atomic_state *state)
+{
+	if (!bridge)
+		return;
+
+	if (bridge->funcs->atomic_enable)
+		bridge->funcs->atomic_enable(bridge, state);
+	else if (bridge->funcs->enable)
+		bridge->funcs->enable(bridge);
+
+	drm_atomic_bridge_enable(bridge->next, state);
+}
+EXPORT_SYMBOL(drm_atomic_bridge_enable);
+
 #ifdef CONFIG_OF
 /**
  * of_drm_find_bridge - find the bridge corresponding to the device node in