[PATCH 4/6] drm/radeon: reject empty VRAM ranges

[Jiale Yao <yaojiale02@163.com>]

A VRAM size smaller than a page becomes a zero-page TTM range and
causes drm_mm_init() to hit its zero-range BUG check. Reject such a
range before initializing the VRAM manager.

Fixes: 37205891d84f ("drm/ttm: make ttm_range_man_init/takedown take type + args")
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 drivers/gpu/drm/radeon/radeon_ttm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index e7ab8162ac69..925593af1688 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -69,6 +69,9 @@ struct radeon_device *radeon_get_rdev(struct ttm_device *bdev)
 
 static int radeon_ttm_init_vram(struct radeon_device *rdev)
 {
+	if (rdev->mc.real_vram_size < PAGE_SIZE)
+		return -EINVAL;
+
 	return ttm_range_man_init(&rdev->mman.bdev, TTM_PL_VRAM,
 				  false, rdev->mc.real_vram_size >> PAGE_SHIFT);
 }
-- 
2.34.1