Re: [PATCH] drm/amdgpu: Initialise drm_gem_object_funcs for imported BOs

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 08.12.20 um 20:11 schrieb Andrey Grodzovsky:
>
> On 12/8/20 2:01 PM, Christian König wrote:
>> Am 08.12.20 um 19:52 schrieb Andrey Grodzovsky:
>>>
>>> On 12/8/20 1:47 PM, Christian König wrote:
>>>> Am 08.12.20 um 19:44 schrieb Andrey Grodzovsky:
>>>>>
>>>>> On 12/8/20 1:29 PM, Christian König wrote:
>>>>>> Am 08.12.20 um 19:26 schrieb Andrey Grodzovsky:
>>>>>>>
>>>>>>> On 12/8/20 12:36 PM, Christian König wrote:
>>>>>>>> Am 08.12.20 um 18:10 schrieb Andrey Grodzovsky:
>>>>>>>>> For BOs imported from outside of amdgpu, setting of 
>>>>>>>>> amdgpu_gem_object_funcs
>>>>>>>>> was missing in amdgpu_dma_buf_create_obj. Fix by refactoring 
>>>>>>>>> BO creation
>>>>>>>>> and amdgpu_gem_object_funcs setting into single function called
>>>>>>>>> from both code paths.
>>>>>>>>
>>>>>>>> Can you outline why we can't use amdgpu_gem_object_create() 
>>>>>>>> directly?
>>>>>>>>
>>>>>>>> I mean we have a bit of extra error handling in there and we 
>>>>>>>> need to grab the resv lock and set the domains after creation, 
>>>>>>>> but that shouldn't matter and I don't see why that should not 
>>>>>>>> work.
>>>>>>>
>>>>>>>
>>>>>>> On top of what you mentioned you also have 
>>>>>>> bp.domain/bp.preferred_domain being set differently so you need 
>>>>>>> to add another
>>>>>>> argument to amdgpu_gem_object_create to reflect this difference 
>>>>>>> which clutters even more the already cluttered argument list.
>>>>>>
>>>>>> That should be outside of the call to amdgpu_gem_object_create(), 
>>>>>> similar to how it is outside of the amdgpu_bo_create currently.
>>>>>
>>>>>
>>>>> So you agree we have to add another argument to 
>>>>> amdgpu_gem_object_create (e.g. u32 preferred_domain) which will be 
>>>>> 0 for amdgpu_dma_buf_create_obj
>>>>> and equal to initial_domain for all the code path currently 
>>>>> calling amdgpu_gem_object_create ?
>>>>
>>>> No, I just don't see the need for that. We need to overwrite the 
>>>> preferred domain after the function call anyway.
>>>>
>>>> DMA-buf imports are created with the initial domain CPU and then 
>>>> get that overwritten to GTT after creation.
>>>>
>>>>>
>>>>>
>>>>>>
>>>>>>> Regarding the extra error handling - you have the 'retry' dance 
>>>>>>> in amdgpu_gem_object_create which jumps back to the middle of 
>>>>>>> amdgpu_bo_param
>>>>>>> initialization but you don't have it in 
>>>>>>> amdgpu_dma_buf_create_obj which also complicates the reuse of 
>>>>>>> amdgpu_gem_object_create as is.
>>>>>>
>>>>>> Regarding the extra error handling, that kicks in only when 
>>>>>> AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED is specified as flags or 
>>>>>> AMDGPU_GEM_DOMAIN_VRAM as initial domain. Neither is the case here.
>>>>>
>>>>>
>>>>> Yes, still, it makes me a bit uncomfortable relying on internal 
>>>>> implementation details of an API function I call to do the thing I 
>>>>> expect.
>>>>
>>>> Yeah, ok that is a rather good argument.
>>>>
>>>> Christian.
>>>
>>>
>>> So should I just keep it as is or you think it's still would be more 
>>> beneficial to unify them the way you propose ?
>>
>> Maybe we should move the error handling into 
>> amdgpu_gem_create_ioctl() anyway.
>>
>> We don't really want that handling in the userptr stuff and for the 
>> call from amdgpufb_create_pinned_object() that is actually a bug!
>>
>> E.g. for the fb emulation we can't fall back from VRAM to GTT like in 
>> the create ioctl.
>
>
> What about amdgpu_mode_dumb_create, seems like there GTT domain is 
> also relevant and so the error handling would be needed there too.

Nope, same thing as with the fb emulation:

>         domain = amdgpu_bo_get_preferred_pin_domain(adev,
> amdgpu_display_supported_domains(adev, flags));

This BO is created for scanout, falling back to GTT because we don't 
have enough memory or clearing the CPU access flag is most likely a bug 
here.

Christian.

>
> Andrey
>
>
>>
>> Christian.
>>
>>>
>>> Andrey
>>>
>>>
>>>>
>>>>>
>>>>> Andrey
>>>>>
>>>>>
>>>>>>
>>>>>> Christian.
>>>>>>
>>>>>>>
>>>>>>> Andrey
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Christian.
>>>>>>>>
>>>>>>>>>
>>>>>>>>> This fixes null ptr regression casued by commit
>>>>>>>>> d693def drm: Remove obsolete GEM and PRIME callbacks from 
>>>>>>>>> struct drm_driver
>>>>>>>>>
>>>>>>>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>>>>>>>> ---
>>>>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 13 ++++++-------
>>>>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c     | 22 
>>>>>>>>> +++++++++++++++++-----
>>>>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h     |  5 +++++
>>>>>>>>>   3 files changed, 28 insertions(+), 12 deletions(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c 
>>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>>>>>>>>> index e5919ef..da4d0ab 100644
>>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>>>>>>>>> @@ -405,6 +405,7 @@ struct dma_buf 
>>>>>>>>> *amdgpu_gem_prime_export(struct drm_gem_object *gobj,
>>>>>>>>>       return buf;
>>>>>>>>>   }
>>>>>>>>>   +
>>>>>>>>>   /**
>>>>>>>>>    * amdgpu_dma_buf_create_obj - create BO for DMA-buf import
>>>>>>>>>    *
>>>>>>>>> @@ -424,7 +425,7 @@ amdgpu_dma_buf_create_obj(struct 
>>>>>>>>> drm_device *dev, struct dma_buf *dma_buf)
>>>>>>>>>       struct amdgpu_device *adev = drm_to_adev(dev);
>>>>>>>>>       struct amdgpu_bo *bo;
>>>>>>>>>       struct amdgpu_bo_param bp;
>>>>>>>>> -    int ret;
>>>>>>>>> +    struct drm_gem_object *obj;
>>>>>>>>>         memset(&bp, 0, sizeof(bp));
>>>>>>>>>       bp.size = dma_buf->size;
>>>>>>>>> @@ -434,21 +435,19 @@ amdgpu_dma_buf_create_obj(struct 
>>>>>>>>> drm_device *dev, struct dma_buf *dma_buf)
>>>>>>>>>       bp.type = ttm_bo_type_sg;
>>>>>>>>>       bp.resv = resv;
>>>>>>>>>       dma_resv_lock(resv, NULL);
>>>>>>>>> -    ret = amdgpu_bo_create(adev, &bp, &bo);
>>>>>>>>> -    if (ret)
>>>>>>>>> +    obj = amdgpu_gem_object_create_raw(adev, &bp);
>>>>>>>>> +    if (IS_ERR(obj))
>>>>>>>>>           goto error;
>>>>>>>>>   +    bo = gem_to_amdgpu_bo(obj);
>>>>>>>>>       bo->allowed_domains = AMDGPU_GEM_DOMAIN_GTT;
>>>>>>>>>       bo->preferred_domains = AMDGPU_GEM_DOMAIN_GTT;
>>>>>>>>>       if (dma_buf->ops != &amdgpu_dmabuf_ops)
>>>>>>>>>           bo->prime_shared_count = 1;
>>>>>>>>>   -    dma_resv_unlock(resv);
>>>>>>>>> -    return &bo->tbo.base;
>>>>>>>>> -
>>>>>>>>>   error:
>>>>>>>>>       dma_resv_unlock(resv);
>>>>>>>>> -    return ERR_PTR(ret);
>>>>>>>>> +    return obj;
>>>>>>>>>   }
>>>>>>>>>     /**
>>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c 
>>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>>>>>>>> index c9f94fb..5f22ce6 100644
>>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
>>>>>>>>> @@ -52,13 +52,26 @@ static void amdgpu_gem_object_free(struct 
>>>>>>>>> drm_gem_object *gobj)
>>>>>>>>>       }
>>>>>>>>>   }
>>>>>>>>>   +struct drm_gem_object *amdgpu_gem_object_create_raw(struct 
>>>>>>>>> amdgpu_device *adev,
>>>>>>>>> +                            struct amdgpu_bo_param *bp)
>>>>>>>>> +{
>>>>>>>>> +    struct amdgpu_bo *bo;
>>>>>>>>> +    int r;
>>>>>>>>> +
>>>>>>>>> +    r = amdgpu_bo_create(adev, bp, &bo);
>>>>>>>>> +    if (r)
>>>>>>>>> +        return ERR_PTR(r);
>>>>>>>>> +
>>>>>>>>> +    bo->tbo.base.funcs = &amdgpu_gem_object_funcs;
>>>>>>>>> +    return &bo->tbo.base;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>>   int amdgpu_gem_object_create(struct amdgpu_device *adev, 
>>>>>>>>> unsigned long size,
>>>>>>>>>                    int alignment, u32 initial_domain,
>>>>>>>>>                    u64 flags, enum ttm_bo_type type,
>>>>>>>>>                    struct dma_resv *resv,
>>>>>>>>>                    struct drm_gem_object **obj)
>>>>>>>>>   {
>>>>>>>>> -    struct amdgpu_bo *bo;
>>>>>>>>>       struct amdgpu_bo_param bp;
>>>>>>>>>       int r;
>>>>>>>>>   @@ -73,8 +86,9 @@ int amdgpu_gem_object_create(struct 
>>>>>>>>> amdgpu_device *adev, unsigned long size,
>>>>>>>>>   retry:
>>>>>>>>>       bp.flags = flags;
>>>>>>>>>       bp.domain = initial_domain;
>>>>>>>>> -    r = amdgpu_bo_create(adev, &bp, &bo);
>>>>>>>>> -    if (r) {
>>>>>>>>> +    *obj = amdgpu_gem_object_create_raw(adev, &bp);
>>>>>>>>> +    if (IS_ERR(*obj)) {
>>>>>>>>> +        r = PTR_ERR(*obj);
>>>>>>>>>           if (r != -ERESTARTSYS) {
>>>>>>>>>               if (flags & 
>>>>>>>>> AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED) {
>>>>>>>>>                   flags &= 
>>>>>>>>> ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
>>>>>>>>> @@ -90,8 +104,6 @@ int amdgpu_gem_object_create(struct 
>>>>>>>>> amdgpu_device *adev, unsigned long size,
>>>>>>>>>           }
>>>>>>>>>           return r;
>>>>>>>>>       }
>>>>>>>>> -    *obj = &bo->tbo.base;
>>>>>>>>> -    (*obj)->funcs = &amdgpu_gem_object_funcs;
>>>>>>>>>         return 0;
>>>>>>>>>   }
>>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h 
>>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
>>>>>>>>> index 637bf51..a6b90d3 100644
>>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
>>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.h
>>>>>>>>> @@ -38,12 +38,17 @@ unsigned long amdgpu_gem_timeout(uint64_t 
>>>>>>>>> timeout_ns);
>>>>>>>>>   /*
>>>>>>>>>    * GEM objects.
>>>>>>>>>    */
>>>>>>>>> +
>>>>>>>>> +struct amdgpu_bo_param;
>>>>>>>>> +
>>>>>>>>>   void amdgpu_gem_force_release(struct amdgpu_device *adev);
>>>>>>>>>   int amdgpu_gem_object_create(struct amdgpu_device *adev, 
>>>>>>>>> unsigned long size,
>>>>>>>>>                    int alignment, u32 initial_domain,
>>>>>>>>>                    u64 flags, enum ttm_bo_type type,
>>>>>>>>>                    struct dma_resv *resv,
>>>>>>>>>                    struct drm_gem_object **obj);
>>>>>>>>> +struct drm_gem_object *amdgpu_gem_object_create_raw(struct 
>>>>>>>>> amdgpu_device *adev,
>>>>>>>>> +                            struct amdgpu_bo_param *bp);
>>>>>>>>>     int amdgpu_mode_dumb_create(struct drm_file *file_priv,
>>>>>>>>>                   struct drm_device *dev,
>>>>>>>>
>>>>>>
>>>>
>>
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