drm/omap: dss: Modify omapdss_find_output_from_display() to return channel

The omapdss_find_output_from_display() function is only used to retrieve
the dispc channel corresponding to the display. Return the dispc channel
directly, and rename the function to omapdss_device_get_dispc_channel()
to match its new purpose.

The dssdev->id check is removed as the dssdev is guaranteed to be an
output and have a non-zero id, as proved by the lack of crash despite
the caller never checking the returned pointer before dereferencing it.

As the function is not specific to outputs anymore, move it from
output.c to base.c.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/omapdrm/dss/base.c

@@ -236,6 +236,15 @@ void omapdss_device_disconnect(struct omap_dss_device *src,
 }
 EXPORT_SYMBOL_GPL(omapdss_device_disconnect);
 
+enum omap_channel omapdss_device_get_dispc_channel(struct omap_dss_device *dssdev)
+{
+	while (dssdev->src)
+		dssdev = dssdev->src;
+
+	return dssdev->dispc_channel;
+}
+EXPORT_SYMBOL(omapdss_device_get_dispc_channel);
+
 /* -----------------------------------------------------------------------------
  * Components Handling
  */

drivers/gpu/drm/omapdrm/dss/omapdss.h

@@ -504,6 +504,7 @@ int omapdss_device_connect(struct dss_device *dss,
 			   struct omap_dss_device *dst);
 void omapdss_device_disconnect(struct omap_dss_device *src,
 			       struct omap_dss_device *dst);
+enum omap_channel omapdss_device_get_dispc_channel(struct omap_dss_device *dssdev);
 
 int omap_dss_get_num_overlay_managers(void);
 
@@ -513,8 +514,6 @@ int omapdss_output_set_device(struct omap_dss_device *out,
 		struct omap_dss_device *dssdev);
 int omapdss_output_unset_device(struct omap_dss_device *out);
 
-struct omap_dss_device *omapdss_find_output_from_display(struct omap_dss_device *dssdev);
-
 typedef void (*omap_dispc_isr_t) (void *arg, u32 mask);
 int omap_dispc_register_isr(omap_dispc_isr_t isr, void *arg, u32 mask);
 int omap_dispc_unregister_isr(omap_dispc_isr_t isr, void *arg, u32 mask);

drivers/gpu/drm/omapdrm/dss/output.c

@@ -88,18 +88,6 @@ int omapdss_output_unset_device(struct omap_dss_device *out)
 }
 EXPORT_SYMBOL(omapdss_output_unset_device);
 
-struct omap_dss_device *omapdss_find_output_from_display(struct omap_dss_device *dssdev)
-{
-	while (dssdev->src)
-		dssdev = dssdev->src;
-
-	if (dssdev->id != 0)
-		return omapdss_device_get(dssdev);
-
-	return NULL;
-}
-EXPORT_SYMBOL(omapdss_find_output_from_display);
-
 int dss_install_mgr_ops(struct dss_device *dss,
 			const struct dss_mgr_ops *mgr_ops,
 			struct omap_drm_private *priv)

drivers/gpu/drm/omapdrm/omap_crtc.c

@@ -699,12 +699,9 @@ struct drm_crtc *omap_crtc_init(struct drm_device *dev,
 	struct drm_crtc *crtc = NULL;
 	struct omap_crtc *omap_crtc;
 	enum omap_channel channel;
-	struct omap_dss_device *out;
 	int ret;
 
-	out = omapdss_find_output_from_display(dssdev);
-	channel = out->dispc_channel;
-	omapdss_device_put(out);
+	channel = omapdss_device_get_dispc_channel(dssdev);
 
 	DBG("%s", channel_names[channel]);