drm/bridge: imx: Remove redundant checks on existence of bridge->encoder

The checks on the existence of bridge->encoder in the implementation of
drm_bridge_funcs::attach() is not necessary, as it has already been checked
in the drm_bridge_attach() function call by previous bridge or KMS driver.
The drm_bridge_attach() will quit with a negative error code returned if
it fails for some reasons, hence, it is guaranteed that the .encoder member
of the drm_bridge instance is not NULL when various i.MX specific bridge
attach functions are called.

Remove the redundant checking codes "if (!bridge->encoder) { ... }".
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240513153109.46786-12-sui.jingfeng@linux.dev

drivers/gpu/drm/bridge/imx/imx-ldb-helper.c

@@ -116,11 +116,6 @@ int ldb_bridge_attach_helper(struct drm_bridge *bridge,
 		return -EINVAL;
 	}
 
-	if (!bridge->encoder) {
-		DRM_DEV_ERROR(ldb->dev, "missing encoder\n");
-		return -ENODEV;
-	}
-
 	return drm_bridge_attach(bridge->encoder,
 				ldb_ch->next_bridge, bridge,
 				DRM_BRIDGE_ATTACH_NO_CONNECTOR);

drivers/gpu/drm/bridge/imx/imx8qxp-pixel-combiner.c

@@ -119,11 +119,6 @@ static int imx8qxp_pc_bridge_attach(struct drm_bridge *bridge,
 		return -EINVAL;
 	}
 
-	if (!bridge->encoder) {
-		DRM_DEV_ERROR(pc->dev, "missing encoder\n");
-		return -ENODEV;
-	}
-
 	return drm_bridge_attach(bridge->encoder,
 				 ch->next_bridge, bridge,
 				 DRM_BRIDGE_ATTACH_NO_CONNECTOR);

drivers/gpu/drm/bridge/imx/imx8qxp-pixel-link.c

@@ -138,11 +138,6 @@ static int imx8qxp_pixel_link_bridge_attach(struct drm_bridge *bridge,
 		return -EINVAL;
 	}
 
-	if (!bridge->encoder) {
-		DRM_DEV_ERROR(pl->dev, "missing encoder\n");
-		return -ENODEV;
-	}
-
 	return drm_bridge_attach(bridge->encoder,
 				 pl->next_bridge, bridge,
 				 DRM_BRIDGE_ATTACH_NO_CONNECTOR);

drivers/gpu/drm/bridge/imx/imx8qxp-pxl2dpi.c

@@ -58,11 +58,6 @@ static int imx8qxp_pxl2dpi_bridge_attach(struct drm_bridge *bridge,
 		return -EINVAL;
 	}
 
-	if (!bridge->encoder) {
-		DRM_DEV_ERROR(p2d->dev, "missing encoder\n");
-		return -ENODEV;
-	}
-
 	return drm_bridge_attach(bridge->encoder,
 				 p2d->next_bridge, bridge,
 				 DRM_BRIDGE_ATTACH_NO_CONNECTOR);