TTM and AGP conflicts

[Alex Deucher]

On Thu, Dec 22, 2011 at 4:56 PM, James Simmons <jsimmons at infradead.org> wrote:
>
> Hi!
>
>        I updated the openchrome tree and while testing on the AGP system
> discovered some interesting problems with the new TTM changes. The
> problems center around the ttm_tt_[un]populate which I modeled after the
> radeon and nouveau driver.
>        First problem I noticed was on a AGP system that my ttm_tt_populate
> function would oops. Tracking it down I found the problem was the
> ttm_agp_tt_create calls ttm_tt_init instead of ttm_dma_tt_init so once my
> ttm_tt_populate function would attempt to touch the dma_address it would
> oops. The second issue is the assumption of the cast for struct ttm_tt in
> both the populate and unpopulate function. For the AGP case the proper
> case would be to ttm_agp_backend.
>        At this point my assumption is the ttm_bo_move function has to be
> rewritten to handle the AGP case to avoid calling ttm_tt_bind and in all
> cases ttm_tt_bind needs to be avoided. Looking at the radeon and nouveau
> drivers I don't see that testing happening. Am I just missing something?

Happens on AGP radeons as well:
https://bugs.freedesktop.org/show_bug.cgi?id=43719

Alex

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