drm/amdgpu: allow zero as vram limit

This allows testing the driver without any VRAM.
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -150,7 +150,7 @@ struct amdgpu_watchdog_timer
  * Modules parameters.
  */
 extern int amdgpu_modeset;
-extern int amdgpu_vram_limit;
+extern unsigned int amdgpu_vram_limit;
 extern int amdgpu_vis_vram_limit;
 extern int amdgpu_gart_size;
 extern int amdgpu_gtt_size;

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -113,7 +113,7 @@
 #define KMS_DRIVER_MINOR	50
 #define KMS_DRIVER_PATCHLEVEL	0
 
-int amdgpu_vram_limit;
+unsigned int amdgpu_vram_limit = UINT_MAX;
 int amdgpu_vis_vram_limit;
 int amdgpu_gart_size = -1; /* auto */
 int amdgpu_gtt_size = -1; /* auto */

drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c

@@ -206,7 +206,7 @@ void amdgpu_gmc_vram_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc,
 
 	mc->vram_start = base;
 	mc->vram_end = mc->vram_start + mc->mc_vram_size - 1;
-	if (limit && limit < mc->real_vram_size)
+	if (limit < mc->real_vram_size)
 		mc->real_vram_size = limit;
 
 	if (vis_limit && vis_limit < mc->visible_vram_size)