Re: [PATCH -next] drm/amdgpu: Use DIV_ROUND_UP_ULL instead of DIV_ROUND_UP

From: He Ying
Date: Thu Jun 10 2021 - 04:41:09 EST


在 2021/6/10 16:20, Christian König 写道:

Am 10.06.21 um 10:20 schrieb He Ying:
When compiling the kernel for MIPS with CONFIG_DRM_AMDGPU = y, errors are
encountered as follows:

drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.o: In function `amdgpu_vram_mgr_new':
amdgpu_vram_mgr.c:(.text+0x740): undefined reference to `__udivdi3'

Making a 64 bit division by a/b (a is uint64_t) is not supported by default
in linux kernel space. Instead, using do_div is OK for this situation. For
this problem, using DIV_ROUND_UP_ULL instead of DIV_ROUND_UP is better.

Already fixed by this patch in drm-next:

commit 691cf8cd7a531dbfcc29d09a23c509a86fd9b24f
Author: Dave Airlie <airlied@xxxxxxxxxx>
Date:   Thu Jun 10 12:59:00 2021 +1000

    drm/amdgpu: use correct rounding macro for 64-bit

    This fixes 32-bit arm build due to lack of 64-bit divides.

OK. Sigh.

Before sending my patch, I searched patches in

but I didn't find this patch. How can I find whether my patch is duplicated

before sending it? Any suggestions?



Fixes: 6a7f76e70fac ("drm/amdgpu: add VRAM manager v2")
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: He Ying <heying24@xxxxxxxxxx>
  drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 9a6df02477ce..436ec246a7da 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -407,7 +407,7 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
          pages_per_node = max_t(uint32_t, pages_per_node,
-        num_nodes = DIV_ROUND_UP(PFN_UP(mem_bytes), pages_per_node);
+        num_nodes = DIV_ROUND_UP_ULL(PFN_UP(mem_bytes), pages_per_node);
        node = kvmalloc(struct_size(node, mm_nodes, num_nodes),