drm/omap: fix missing disable for unused encoder

When an encoder is no longer connected to a crtc, the driver will leave
the encoder enabled.

This patch adds code to track the encoder used for a crtc, and when the
encoder changes, the old one is disabled.
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: NRob Clark <robdclark@gmail.com>

drivers/gpu/drm/omapdrm/omap_crtc.c

@@ -33,6 +33,7 @@ struct omap_crtc {
 	int pipe;
 	enum omap_channel channel;
 	struct omap_overlay_manager_info info;
+	struct drm_encoder *current_encoder;
 
 	/*
 	 * Temporary: eventually this will go away, but it is needed
@@ -594,6 +595,11 @@ static void omap_crtc_pre_apply(struct omap_drm_apply *apply)
 		}
 	}
 
+	if (omap_crtc->current_encoder && encoder != omap_crtc->current_encoder)
+		omap_encoder_set_enabled(omap_crtc->current_encoder, false);
+
+	omap_crtc->current_encoder = encoder;
+
 	if (!omap_crtc->enabled) {
 		set_enabled(&omap_crtc->base, false);
 		if (encoder)