Re: drm/radeon: "ring test failed" on PA-RISC Linux

[Alex Ivanov <gnidorah@p0n4ik.tk>]

Alex,

10.09.2013, в 16:37, Alex Deucher <alexdeucher@gmail.com> написал(а):

> The dummy page isn't really going to help much.  That page is just
> used as a safety placeholder for gart entries that aren't mapped on
> the GPU.  TTM (drivers/gpu/drm/ttm) actually does the allocation of
> the backing pages for the gart.  

> You may want to look there.

Ah, sorry. Indeed. Though, my idea with:

On Tue, Sep 10, 2013 at 5:20 AM, Alex Ivanov <gnidorah@p0n4ik.tk> wrote:

> Thanks! I'll try. Meanwhile i've tried a switch from page_alloc() to
> dma_alloc_coherent() in radeon_dummy_page_*(), which didn't help :(

doesn't make a sense at TTM part as well.

Konrad,

10.09.2013, 17:25, "Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>:
>
> Is this platform enabling the SWIOTLB layer? 

Doesn't look like. 

> The reason I am asking is
> b/c if you do indeed enable it you end up using the TTM DMA pool
> which allocates pages using the dma_alloc_coherent - which means that
> all of the pages that come out of TTM are already 'DMA' mapped.
>
> And that means the radeon_gart_bind and all its friends
> use the DMA addresses that have been constructed by SWIOTLB IOMMU.
>
> Perhaps the PA-RISC IOMMU creates the DMA addresses differently?
>
> When the card gets programmed, you do end up using ttm_agp_bind right?
> I am wondering if something like this:
>
> https://lkml.org/lkml/2010/12/6/512
>
> is needed to pass in the right DMA address?

No idea how to modify ttm_agp_bind() this way, though doesn't matter if
swiotlb isn't used anyway?
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