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    SubjectRe: [PATCH 4/5] radeon/ttm/PCIe: Use dma_addr if TTM has set it.
    On Fri, Jan 28, 2011 at 09:42:48AM -0500, Jerome Glisse wrote:
    > On Thu, Jan 27, 2011 at 4:20 PM, Konrad Rzeszutek Wilk
    > <konrad.wilk@oracle.com> wrote:
    > > On Fri, Jan 07, 2011 at 12:11:43PM -0500, Konrad Rzeszutek Wilk wrote:
    > >> If the TTM layer has used the DMA API to setup pages that are
    > >> TTM_PAGE_FLAG_DMA32 (look at patch titled: "ttm: Utilize the dma_addr_t
    > >> array for pages that are to in DMA32 pool."), lets use it
    > >> when programming the GART in the PCIe type cards.
    > >>
    > >> This patch skips doing the pci_map_page (and pci_unmap_page) if
    > >> there is a DMA addresses passed in for that page. If the dma_address
    > >> is zero (or DMA_ERROR_CODE), then we continue on with our old
    > >> behaviour.
    > >
    > > Hey Jerome,
    > >
    > > I should have CC-ed you earlier but missed that and instead just
    > > CC-ed the mailing list. I was wondering what your thoughts are
    > > about this patchset? Thomas took a look at the patchset and he is OK
    > > but more eyes never hurt.
    > >
    > > FYI, for clarity I hadn't made the old calls that got moved due
    > > to adding of "{" checkpatch.pl compliant. It complains about it being
    > > past 80 characters. I can naturally fix that up, but thought
    > > that it might detract from the nature of the patch.
    >
    > What happen when we don't ask dma32 alloc to ttm ? Will this still
    > work in virtualized environnement ?

    You mean if we don't pass in the TTM_PAGE_FLAG_DMA32? It will go back
    to using the old mechanism - which is to allocate page using
    alloc_page(GFP_HIGHUSER). Which should be OK in baremetal or
    virtualized environment - and as long as the driver uses the page
    for non-DMA type things, or the graphic card is 64-bit capable at which
    point it has no trouble reaching it.

    >
    > Code looks good but GART stuff can be picky, i will try to do a full
    > scale testing in next couple week.

    Thank you! Much appreciated. Would it be OK if I pinged you in two weeks
    time just in case?


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