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

From: Yangyu Chen
Date: Tue Jan 16 2024 - 13:59:39 EST


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 <cyy@xxxxxxxxxxxx>
---
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