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    SubjectRe: regression in ath10k dma allocation
    Hello Hillf,

    On Mon, Aug 19, 2019 at 12:38:38AM +0200, Tobias Klausmann wrote:
    >
    > On 18.08.19 05:13, Hillf Danton wrote:
    > > On Sat, 17 Aug 2019 00:42:48 +0200 Tobias Klausmann wrote:
    > > > Hi Nicolin,
    > > >
    > > > On 17.08.19 00:25, Nicolin Chen wrote:
    > > > > Hi Tobias
    > > > >
    > > > > On Fri, Aug 16, 2019 at 10:16:45PM +0200, Tobias Klausmann wrote:
    > > > > > > do you have CONFIG_DMA_CMA set in your config? If not please make sure
    > > > > > > you have this commit in your testing tree, and if the problem still
    > > > > > > persists it would be a little odd and we'd have to dig deeper:
    > > > > > >
    > > > > > > commit dd3dcede9fa0a0b661ac1f24843f4a1b1317fdb6
    > > > > > > Author: Nicolin Chen <nicoleotsuka@gmail.com>
    > > > > > > Date: Wed May 29 17:54:25 2019 -0700
    > > > > > >
    > > > > > > dma-contiguous: fix !CONFIG_DMA_CMA version of dma_{alloc, free}_contiguous()
    > > > > > yes CONFIG_DMA_CMA is set (=y, see attached config), the commit you mention
    > > > > > above is included, if you have any hints how to go forward, please let me
    > > > > > know!
    > > > > For CONFIG_DMA_CMA=y, by judging the log with error code -12, I
    > > > > feel this one should work for you. Would you please check if it
    > > > > is included or try it out otherwise?
    > > > >
    > > > > dma-contiguous: do not overwrite align in dma_alloc_contiguous()
    > > > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=c6622a425acd1d2f3a443cd39b490a8777b622d7
    > > >
    > > > Thanks for the hint, yet the commit is included and does not fix the
    > > > problem!
    > > >
    > Hi Hillf,
    >
    > i just tested you first hunk (which comes from kernel/dma/direct.c if i'm
    > not mistaken), it did not compile on its own, yet with a tiny bit of work it
    > did, and it does indeed solve the regression. But if using that is the
    > "right" way to do it, not sure, but its not on me to decide.
    >
    > Anyway: Thanks for the hint,
    >
    > Tobias
    >
    >
    > > Hi Tobias
    > >
    > > Two minor diffs below in hope that they might make sense.
    > >
    > > 1, fallback unless dma coherent ok.
    > >
    > > --- a/kernel/dma/contiguous.c
    > > +++ b/kernel/dma/contiguous.c
    > > @@ -246,6 +246,10 @@ struct page *dma_alloc_contiguous(struct
    > > size_t cma_align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
    > > page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN);
    > > + if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
    > > + dma_free_contiguous(dev, page, size);
    > > + page = NULL;
    > > + }

    Right...the condition was in-between. However, not every caller
    of dma_alloc_contiguous() is supposed to have a coherent check.
    So we either add a 'bool coherent_ok' to the API or revert the
    dma-direct part back to the original. Probably former option is
    better?

    Thank you for the debugging. I have been a bit distracted, may
    not be able to submit a fix very soon. Would you like to help?

    Thanks!
    Nicolin

    > > }
    > > /* Fallback allocation of normal pages */
    > > --
    > >
    > > 2, cleanup: cma unless contiguous
    > >
    > > --- a/kernel/dma/contiguous.c
    > > +++ b/kernel/dma/contiguous.c
    > > @@ -234,18 +234,13 @@ struct page *dma_alloc_contiguous(struct
    > > size_t count = PAGE_ALIGN(size) >> PAGE_SHIFT;
    > > size_t align = get_order(PAGE_ALIGN(size));
    > > struct page *page = NULL;
    > > - struct cma *cma = NULL;
    > > -
    > > - if (dev && dev->cma_area)
    > > - cma = dev->cma_area;
    > > - else if (count > 1)
    > > - cma = dma_contiguous_default_area;
    > > /* CMA can be used only in the context which permits sleeping */
    > > - if (cma && gfpflags_allow_blocking(gfp)) {
    > > + if (count > 1 && gfpflags_allow_blocking(gfp)) {
    > > size_t cma_align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
    > > - page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN);
    > > + page = cma_alloc(dev_get_cma_area(dev), count, cma_align,
    > > + gfp & __GFP_NOWARN);
    > > if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
    > > dma_free_contiguous(dev, page, size);
    > > page = NULL;
    > > --
    > >

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