From: Eric Anholt <eric@anholt.net>
Date: Mon, 23 Apr 2018 17:46:08 -0700
Subject: drm: Make the prime vmap/vunmap hooks optional.
Git-commit: d34deab907605a81eec83afe006fad2e5b4673b4
Patch-mainline: v4.18-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Some drivers leave these unimplemented, so don't make them have
unimplemented stubs.

Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180424004610.4637-2-eric@anholt.net
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/drm_prime.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -409,7 +409,10 @@ void *drm_gem_dmabuf_vmap(struct dma_buf
 	struct drm_gem_object *obj = dma_buf->priv;
 	struct drm_device *dev = obj->dev;
 
-	return dev->driver->gem_prime_vmap(obj);
+	if (dev->driver->gem_prime_vmap)
+		return dev->driver->gem_prime_vmap(obj);
+	else
+		return NULL;
 }
 EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
 
@@ -426,7 +429,8 @@ void drm_gem_dmabuf_vunmap(struct dma_bu
 	struct drm_gem_object *obj = dma_buf->priv;
 	struct drm_device *dev = obj->dev;
 
-	dev->driver->gem_prime_vunmap(obj, vaddr);
+	if (dev->driver->gem_prime_vunmap)
+		dev->driver->gem_prime_vunmap(obj, vaddr);
 }
 EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);