Re: TTM and AGP conflicts

[Thomas Hellstrom <thellstrom@vmware.com>]

On 01/06/2012 04:51 PM, James Simmons wrote:
>    
>>>> You can achieve what you want by either adding a new domain so you would have
>>>> system, vram, agp, pcidma and object can be bound to one and only one. Or you
>>>> can hack your own agp ttm backend that could bind bo to agp or pci or
>>>> both at the same time depending on what you want to achieve.
>>>>          
>>> The question is how does one know which domain you want in tt_create.
>>> Currenty drivers are using there dev_priv but if you have have more than
>>> one option available how does one choose? Would you be okay with passing
>>> in a domain flag?
>>>
>>>        
>> Well i agree that something would be usefull there so the driver know
>> which bind/unbind function it should use. Thomas i would prefer
>> passing the bo to the tt_create callback but a flag is the minimum we
>> need.
>>      
> We can discuss this after the merge widow. Jerome your patch does fix a
> regression whereas my proposal is a enhancement.
>    

..Back from parental leave.

I'm not 100% sure I understand the problem correctly, but I assume the 
problem is that
you receive a "bind" request for pages allocated out of the wrong DMA 
pool? Is that correct?

In that case we need to make both the following happen:
1) The backend should be required to supply a fallback that can bind 
anyway by allocating the correct page type and copy.
2) I'm OK with providing a hint to tt_create. IIRC we're passing bo::mem 
to tt_bind. Would it be ok to pass the same to tt_create?

/Thomas