linux-kernel - Re: [PATCH -next] drm/amdgpu: Use DIV_ROUND_UP_ULL instead of DIV_ROUND

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Message-ID: <ef947327-6114-6c22-6107-bdb9c72f3dfe@huawei.com>
Date:   Thu, 10 Jun 2021 16:41:03 +0800
From:   He Ying <heying24@...wei.com>
To:     Christian König <christian.koenig@....com>,
        <alexander.deucher@....com>, <Xinhui.Pan@....com>,
        <airlied@...ux.ie>, <daniel@...ll.ch>, <airlied@...hat.com>,
        <bskeggs@...hat.com>, <matthew.auld@...el.com>,
        <Ramesh.Errabolu@....com>, <mchehab+huawei@...nel.org>,
        <Dennis.Li@....com>, <funfunctor@...klore1984.net>
CC:     <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] drm/amdgpu: Use DIV_ROUND_UP_ULL instead of
 DIV_ROUND_UP

Hello,


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@...hat.com>
> 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 https://lore.kernel.org/lkml/

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

before sending it? Any suggestions?


Thanks.

>
> Regards,
> Christian.
>
>>
>> Fixes: 6a7f76e70fac ("drm/amdgpu: add VRAM manager v2")
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Signed-off-by: He Ying <heying24@...wei.com>
>> ---
>>   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,
>>   #endif
>>           pages_per_node = max_t(uint32_t, pages_per_node,
>>                          tbo->page_alignment);
>> -        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),
>
> .