[PATCH v2 1/1] drm/ttm: allocate dummy_read_page without DMA32 on fail

[Yangyu Chen]

Some platforms may not have any memory in ZONE_DMA32 and use IOMMU to allow
32-bit-DMA-only device to work. Forcing GFP_DMA32 on dummy_read_page will
fail on such platforms. Retry after fail will get this works on such
platforms.

Signed-off-by: Yangyu Chen <c...@cyyself.name>
---
 drivers/gpu/drm/ttm/ttm_device.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index d48b39132b32..c9fa8561f71f 100644
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -95,11 +95,17 @@ static int ttm_global_init(void)
        ttm_pool_mgr_init(num_pages);
        ttm_tt_mgr_init(num_pages, num_dma32);
 
-       glob->dummy_read_page = alloc_page(__GFP_ZERO | GFP_DMA32);
+       glob->dummy_read_page = alloc_page(__GFP_ZERO | GFP_DMA32 |
+                                          __GFP_NOWARN);
 
+       /* Retry without GFP_DMA32 for platforms DMA32 is not available */
        if (unlikely(glob->dummy_read_page == NULL)) {
-               ret = -ENOMEM;
-               goto out;
+               glob->dummy_read_page = alloc_page(__GFP_ZERO);
+               if (unlikely(glob->dummy_read_page == NULL)) {
+                       ret = -ENOMEM;
+                       goto out;
+               }
+               pr_warn("Using GFP_DMA32 fallback for dummy_read_page\n");
        }
 
        INIT_LIST_HEAD(&glob->device_list);
-- 
2.43.0