drm/bridge: analogix_dp: Improve panel on time

In order to reduce the time required to turn on the panel, this patch
makes 2 assumptions:
1- In detect(): if there's a panel, we're connected.
2- In get_modes(): if there's a panel, let the panel driver decide if
   it should prepare/unprepare in order to get the modes.

The first is straightforward, and shouldn't need further explanation. The
second should eliminate the prepare/unprepare delays from get_modes() in
most cases, since panels generally hardcode their modes in the driver as
opposed to reading EDID. If a panel does need to read EDID, it should be
responsible for ensuring it's in a state in which it can.

Signed-off-by: Sean Paul <seanpaul@chromium.org>

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index e9c9aeb..18f622a 100644 (file)
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -924,15 +924,15 @@ int analogix_dp_get_modes(struct drm_connector *connector)
        struct edid *edid;
        int ret, num_modes = 0;
 
-       ret = analogix_dp_prepare_panel(dp, true, false);
-       if (ret) {
-               DRM_ERROR("Failed to prepare panel (%d)\n", ret);
-               return 0;
-       }
-
        if (dp->plat_data->panel) {
                num_modes += drm_panel_get_modes(dp->plat_data->panel);
        } else {
+               ret = analogix_dp_prepare_panel(dp, true, false);
+               if (ret) {
+                       DRM_ERROR("Failed to prepare panel (%d)\n", ret);
+                       return 0;
+               }
+
                edid = drm_get_edid(connector, &dp->aux.ddc);
                if (edid) {
                        drm_mode_connector_update_edid_property(&dp->connector,
@@ -940,15 +940,15 @@ int analogix_dp_get_modes(struct drm_connector *connector)
                        num_modes += drm_add_edid_modes(&dp->connector, edid);
                        kfree(edid);
                }
+
+               ret = analogix_dp_prepare_panel(dp, false, false);
+               if (ret)
+                       DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
        }
 
        if (dp->plat_data->get_modes)
                num_modes += dp->plat_data->get_modes(dp->plat_data, connector);
 
-       ret = analogix_dp_prepare_panel(dp, false, false);
-       if (ret)
-               DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
-
        return num_modes;
 }
 
@@ -972,6 +972,9 @@ analogix_dp_detect(struct drm_connector *connector, bool force)
        enum drm_connector_status status = connector_status_disconnected;
        int ret;
 
+       if (dp->plat_data->panel)
+               return connector_status_connected;
+
        ret = analogix_dp_prepare_panel(dp, true, false);
        if (ret) {
                DRM_ERROR("Failed to prepare panel (%d)\n", ret);