[PATCH] drm/i915: Fix 32-bit build

[PATCH] drm/i915: Fix 32-bit build

[Guenter Roeck]

Commit aff1e0b09b54 ("drm/i915/ttm: fix sg_table construction") introduces
an additional parameter to i915_rsgt_from_mm_node(). The parameter is used
to calculate segment_pages. This in turn is used in DIV_ROUND_UP() as
divisor. So far segment_pages was a constant and handled without divide
operation. Since it is no longer constant, a divide operation is now
necessary. This results in build errors on 32-bit builds.

x86_64-linux-ld: drivers/gpu/drm/i915/i915_scatterlist.o:
	in function `i915_rsgt_from_mm_node':
i915_scatterlist.c:(.text+0x196): undefined reference to `__udivdi3'

Fix the problem by using DIV_ROUND_UP_ULL() instead of DIV_ROUND_UP().

Fixes: aff1e0b09b54 ("drm/i915/ttm: fix sg_table construction")
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
I took a stab at the problem. Please ignore the noise if it has already
been fixed with a different patch.

 drivers/gpu/drm/i915/i915_scatterlist.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c b/drivers/gpu/drm/i915/i915_scatterlist.c
index f63b50b71e10..b81d5658c222 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.c
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -96,7 +96,7 @@ struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
 
 	i915_refct_sgt_init(rsgt, node->size << PAGE_SHIFT);
 	st = &rsgt->table;
-	if (sg_alloc_table(st, DIV_ROUND_UP(node->size, segment_pages),
+	if (sg_alloc_table(st, DIV_ROUND_UP_ULL(node->size, segment_pages),
 			   GFP_KERNEL)) {
 		i915_refct_sgt_put(rsgt);
 		return ERR_PTR(-ENOMEM);
-- 
2.36.2

Re: [PATCH] drm/i915: Fix 32-bit build

[Vivi, Rodrigo]

On Sun, 2022-07-17 at 09:20 -0700, Guenter Roeck wrote:
> Commit aff1e0b09b54 ("drm/i915/ttm: fix sg_table construction")
> introduces
> an additional parameter to i915_rsgt_from_mm_node(). The parameter is
> used
> to calculate segment_pages. This in turn is used in DIV_ROUND_UP() as
> divisor. So far segment_pages was a constant and handled without
> divide
> operation. Since it is no longer constant, a divide operation is now
> necessary. This results in build errors on 32-bit builds.
> 
> x86_64-linux-ld: drivers/gpu/drm/i915/i915_scatterlist.o:
>         in function `i915_rsgt_from_mm_node':
> i915_scatterlist.c:(.text+0x196): undefined reference to `__udivdi3'
> 
> Fix the problem by using DIV_ROUND_UP_ULL() instead of
> DIV_ROUND_UP().
> 
> Fixes: aff1e0b09b54 ("drm/i915/ttm: fix sg_table construction")
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Nirmoy Das <nirmoy.das@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> I took a stab at the problem. Please ignore the noise if it has
> already
> been fixed with a different patch.

Thanks for your patch.

This was actually fixed already in our -next branches, but missed
on the fixes:

https://patchwork.freedesktop.org/patch/493637/?series=106260&rev=1

Thanks,
Rodrigo.


> 
>  drivers/gpu/drm/i915/i915_scatterlist.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c
> b/drivers/gpu/drm/i915/i915_scatterlist.c
> index f63b50b71e10..b81d5658c222 100644
> --- a/drivers/gpu/drm/i915/i915_scatterlist.c
> +++ b/drivers/gpu/drm/i915/i915_scatterlist.c
> @@ -96,7 +96,7 @@ struct i915_refct_sgt *i915_rsgt_from_mm_node(const
> struct drm_mm_node *node,
>  
>         i915_refct_sgt_init(rsgt, node->size << PAGE_SHIFT);
>         st = &rsgt->table;
> -       if (sg_alloc_table(st, DIV_ROUND_UP(node->size,
> segment_pages),
> +       if (sg_alloc_table(st, DIV_ROUND_UP_ULL(node->size,
> segment_pages),
>                            GFP_KERNEL)) {
>                 i915_refct_sgt_put(rsgt);
>                 return ERR_PTR(-ENOMEM);