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SubjectRe: [PATCH] kernel/dma: export dma_alloc_from_contiguous to modules
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On Thu, 2019-07-11 at 09:50 +0100, Robin Murphy wrote:
> On 11/07/2019 06:33, miles.chen@mediatek.com wrote:
> > From: Miles Chen <miles.chen@mediatek.com>
> >
> > This change exports dma_alloc_from_contiguous and
> > dma_release_from_contiguous to modules.
> >
> > Currently, we can add a reserve a memory node in dts files, make
> > it a CMA memory by setting compatible = "shared-dma-pool",
> > and setup the dev->cma_area by using of_reserved_mem_device_init_by_idx().
> >
> > Export dma_alloc_from_contiguous and dma_release_from_contiguous, so we
> > can allocate/free from/to dev->cma_area in kernel modules.
>
> As far as I understand, this was never intended for drivers to call
> directly. If a device has its own private CMA area, then regular
> dma_alloc_attrs() should allocate from that automatically; if that's not
> happening already, then there's a bug somewhere.
>
> Robin.

Thanks for your comment.
After using dma_direct_ops, dma_alloc_attrs() works fine now.

Miles

>
> > Signed-off-by: Miles Chen <miles.chen@mediatek.com>
> > ---
> > kernel/dma/contiguous.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> > index b2a87905846d..d5920bdedc77 100644
> > --- a/kernel/dma/contiguous.c
> > +++ b/kernel/dma/contiguous.c
> > @@ -197,6 +197,7 @@ struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
> >
> > return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
> > }
> > +EXPORT_SYMBOL_GPL(dma_alloc_from_contiguous);
> >
> > /**
> > * dma_release_from_contiguous() - release allocated pages
> > @@ -213,6 +214,7 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages,
> > {
> > return cma_release(dev_get_cma_area(dev), pages, count);
> > }
> > +EXPORT_SYMBOL_GPL(dma_release_from_contiguous);
> >
> > /*
> > * Support for reserved memory regions defined in device tree
> >


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