Re: [PATCH v3 0/8] dma-buf: heaps: Turn heaps into modules

[Marek Szyprowski]

Hi Maxime,

On 03.03.2026 11:13, Maxime Ripard wrote:
> The recent introduction of heaps in the optee driver [1] made possible
> the creation of heaps as modules.
>
> It's generally a good idea if possible, including for the already
> existing system and CMA heaps.
>
> The system one is pretty trivial, the CMA one is a bit more involved,
> especially since we have a call from kernel/dma/contiguous.c to the CMA
> heap code. This was solved by turning the logic around and making the
> CMA heap call into the contiguous DMA code.
>
> Let me know what you think,
> Maxime
>
> 1: https://lore.kernel.org/dri-devel/20250911135007.1275833-4-jens.wiklander@xxxxxxxxxx/
>
> Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>

I'm okay with the kernel/dma/contiguous.c changes. I only wonder how to 
properly merge them. There are other pending changes to 
kernel/dma/contiguous.c file [1] and if they finally get reviewed, I 
would like to merge both via dma-mapping-for-next tree. Then I can 
provide a stable branch for merging the remaining dma-buf pathes. Is it 
okay for You?

1. 
https://lore.kernel.org/all/20260313150802.1121442-1-m.szyprowski@xxxxxxxxxxx/ 



> ---
> Changes in v3:
> - Squashed cma_get_name and cma_alloc/release patches
> - Fixed typo in Export dev_get_cma_area commit title
> - Fixed compilation failure with DMA_CMA but not OF_RESERVED_MEM
> - Link to v2: https://lore.kernel.org/r/20260227-dma-buf-heaps-as-modules-v2-0-454aee7e06cc@xxxxxxxxxx
>
> Changes in v2:
> - Collect tags
> - Don't export dma_contiguous_default_area anymore, but export
>    dev_get_cma_area instead
> - Mentioned that heap modules can't be removed
> - Link to v1: https://lore.kernel.org/r/20260225-dma-buf-heaps-as-modules-v1-0-2109225a090d@xxxxxxxxxx
>
> ---
> Maxime Ripard (8):
>        dma: contiguous: Turn heap registration logic around
>        dma: contiguous: Make dev_get_cma_area() a proper function
>        dma: contiguous: Make dma_contiguous_default_area static
>        dma: contiguous: Export dev_get_cma_area()
>        mm: cma: Export cma_alloc(), cma_release() and cma_get_name()
>        dma-buf: heaps: Export mem_accounting parameter
>        dma-buf: heaps: cma: Turn the heap into a module
>        dma-buf: heaps: system: Turn the heap into a module
>
>   drivers/dma-buf/dma-heap.c          |  1 +
>   drivers/dma-buf/heaps/Kconfig       |  4 ++--
>   drivers/dma-buf/heaps/cma_heap.c    | 21 +++++----------------
>   drivers/dma-buf/heaps/system_heap.c |  5 +++++
>   include/linux/dma-map-ops.h         | 18 ++++++++++--------
>   kernel/dma/contiguous.c             | 37 ++++++++++++++++++++++++++++++++++---
>   mm/cma.c                            |  3 +++
>   7 files changed, 60 insertions(+), 29 deletions(-)
> ---
> base-commit: 499a718536dc0e1c1d1b6211847207d58acd9916
> change-id: 20260225-dma-buf-heaps-as-modules-1034b3ec9f2a
>
> Best regards,

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland