Re: [PATCH] kernel/dma: export dma_alloc_from_contiguous to modules

From: Robin Murphy
Date: Thu Jul 11 2019 - 04:51:03 EST

On 11/07/2019 06:33, miles.chen@xxxxxxxxxxxx wrote:
From: Miles Chen <miles.chen@xxxxxxxxxxxx>

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.


Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
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);
* 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);
* Support for reserved memory regions defined in device tree