[PATCH v2 13/15] drm/ttm: Add BO and offset arguments for vm_access and vm_fault ttm handlers.

[Christian König]

Am 18.05.21 um 17:11 schrieb Thomas Hellström:
>
> On 5/18/21 5:07 PM, Christian König wrote:
>> Am 18.05.21 um 16:55 schrieb Thomas Hellström:
>>> From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>>
>>> This allows other drivers that may not setup the vma in the same way
>>> to use the ttm bo helpers.
>>
>> Uff can you please explain why exactly you need that?
>>
>> Providing the BO is not much of a problem, but having the BO at 
>> different VMA offsets is really a no-go with TTM.
>>
>> Christian.
>
> The current i915 uapi is using different offsets for different caching 
> :/. We're currently working around that by using ttm_bo_type_kernel 
> (no TTM vma offset at all) and i915's offset.

Can you instead adjust the offset in the mmap callback like we do for 
dma-buf?

That's really a no-go what you describe here because it will mess up 
reverse mapping lockup for buffer movement.

Christian.

>
> /Thomas
>