drm: Hook up DPMS property handling in drm_crtc.c. Add drm_helper_connector_dpms.

Making the drm_crtc.c code recognize the DPMS property and invoke the
connector->dpms function doesn't remove any capability from the driver while
reducing code duplication.

That just highlighted the problem with the existing DPMS functions which
could turn off the connector, but failed to turn off any relevant crtcs. The
new drm_helper_connector_dpms function manages all of that, using the
drm_helper-specific crtc and encoder dpms functions, automatically computing
the appropriate DPMS level for each object in the system.

This fixes the current troubles in the i915 driver which left PLLs, pipes
and planes running while in DPMS_OFF mode or even while they were unused.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 107 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 45890447fee..a6f73f1e99d 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -199,6 +199,29 @@ static void drm_helper_add_std_modes(struct drm_device *dev,
 }
 
 /**
+ * drm_helper_encoder_in_use - check if a given encoder is in use
+ * @encoder: encoder to check
+ *
+ * LOCKING:
+ * Caller must hold mode config lock.
+ *
+ * Walk @encoders's DRM device's mode_config and see if it's in use.
+ *
+ * RETURNS:
+ * True if @encoder is part of the mode_config, false otherwise.
+ */
+bool drm_helper_encoder_in_use(struct drm_encoder *encoder)
+{
+	struct drm_connector *connector;
+	struct drm_device *dev = encoder->dev;
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+		if (connector->encoder == encoder)
+			return true;
+	return false;
+}
+EXPORT_SYMBOL(drm_helper_encoder_in_use);
+
+/**
  * drm_helper_crtc_in_use - check if a given CRTC is in a mode_config
  * @crtc: CRTC to check
  *
@@ -216,7 +239,7 @@ bool drm_helper_crtc_in_use(struct drm_crtc *crtc)
 	struct drm_device *dev = crtc->dev;
 	/* FIXME: Locking around list access? */
 	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head)
-		if (encoder->crtc == crtc)
+		if (encoder->crtc == crtc && drm_helper_encoder_in_use(encoder))
 			return true;
 	return false;
 }
@@ -240,7 +263,7 @@ void drm_helper_disable_unused_functions(struct drm_device *dev)
 
 	list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
 		encoder_funcs = encoder->helper_private;
-		if (!encoder->crtc)
+		if (!drm_helper_encoder_in_use(encoder))
 			(*encoder_funcs->dpms)(encoder, DRM_MODE_DPMS_OFF);
 	}
 
@@ -935,6 +958,88 @@ bool drm_helper_initial_config(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_helper_initial_config);
 
+static int drm_helper_choose_encoder_dpms(struct drm_encoder *encoder)
+{
+	int dpms = DRM_MODE_DPMS_OFF;
+	struct drm_connector *connector;
+	struct drm_device *dev = encoder->dev;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+		if (connector->encoder == encoder)
+			if (connector->dpms < dpms)
+				dpms = connector->dpms;
+	return dpms;
+}
+
+static int drm_helper_choose_crtc_dpms(struct drm_crtc *crtc)
+{
+	int dpms = DRM_MODE_DPMS_OFF;
+	struct drm_connector *connector;
+	struct drm_device *dev = crtc->dev;
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
+		if (connector->encoder && connector->encoder->crtc == crtc)
+			if (connector->dpms < dpms)
+				dpms = connector->dpms;
+	return dpms;
+}
+
+/**
+ * drm_helper_connector_dpms
+ * @connector affected connector
+ * @mode DPMS mode
+ *
+ * Calls the low-level connector DPMS function, then
+ * calls appropriate encoder and crtc DPMS functions as well
+ */
+void drm_helper_connector_dpms(struct drm_connector *connector, int mode)
+{
+	struct drm_encoder *encoder = connector->encoder;
+	struct drm_crtc *crtc = encoder ? encoder->crtc : NULL;
+	int old_dpms;
+
+	if (mode == connector->dpms)
+		return;
+
+	old_dpms = connector->dpms;
+	connector->dpms = mode;
+
+	/* from off to on, do crtc then encoder */
+	if (mode < old_dpms) {
+		if (crtc) {
+			struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+			if (crtc_funcs->dpms)
+				(*crtc_funcs->dpms) (crtc,
+						     drm_helper_choose_crtc_dpms(crtc));
+		}
+		if (encoder) {
+			struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
+			if (encoder_funcs->dpms)
+				(*encoder_funcs->dpms) (encoder,
+							drm_helper_choose_encoder_dpms(encoder));
+		}
+	}
+
+	/* from on to off, do encoder then crtc */
+	if (mode > old_dpms) {
+		if (encoder) {
+			struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
+			if (encoder_funcs->dpms)
+				(*encoder_funcs->dpms) (encoder,
+							drm_helper_choose_encoder_dpms(encoder));
+		}
+		if (crtc) {
+			struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+			if (crtc_funcs->dpms)
+				(*crtc_funcs->dpms) (crtc,
+						     drm_helper_choose_crtc_dpms(crtc));
+		}
+	}
+
+	return;
+}
+EXPORT_SYMBOL(drm_helper_connector_dpms);
+
 /**
  * drm_hotplug_stage_two
  * @dev DRM device