[RFC 06/16] drm/nouveau/bar: only ioremap BAR3 if it exists

[Alexandre Courbot <acourbot@nvidia.com>]

Some chips that use system memory exclusively (e.g. GK20A) do not
expose 2 BAR regions. For them only BAR1 exists, and it should be used
for USERD mapping. Do not map BAR3 if its resource does not exist.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 drivers/gpu/drm/nouveau/core/subdev/bar/base.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/core/subdev/bar/base.c b/drivers/gpu/drm/nouveau/core/subdev/bar/base.c
index bdf5941..d713eeb 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/bar/base.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/bar/base.c
@@ -110,6 +110,7 @@ nouveau_bar_create_(struct nouveau_object *parent,
 {
 	struct nouveau_device *device = nv_device(parent);
 	struct nouveau_bar *bar;
+	bool has_bar3 = nv_device_resource_len(device, 3) != 0;
 	int ret;
 
 	ret = nouveau_subdev_create_(parent, engine, oclass, 0, "BARCTL",
@@ -118,8 +119,10 @@ nouveau_bar_create_(struct nouveau_object *parent,
 	if (ret)
 		return ret;
 
-	bar->iomem = ioremap(nv_device_resource_start(device, 3),
-			     nv_device_resource_len(device, 3));
+	if (has_bar3)
+		bar->iomem = ioremap(nv_device_resource_start(device, 3),
+				     nv_device_resource_len(device, 3));
+
 	return 0;
 }
 
-- 
1.8.5.3