Re: [PATCH] dma/contiguous: Fix broken build

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 30.03.2026 10:40, Maxime Ripard wrote:
> Commit 3a236f6a5cf2 ("dma: contiguous: Turn heap registration logic
> around") didn't remove one last call to dma_heap_cma_register_heap()
> that it removed, thus breaking the build.
>
> That last call is in dma_contiguous_reserve(), to handle the
> registration of the default CMA region heap instance if it's declared in
> the device tree.
>
> However, the default CMA region instance is already handled by
> retrieving it through dev_get_cma_area() in the CMA heap driver, so the
> call to dma_heap_cma_register_heap() wasn't actually needed.
>
> Let's remove this call, the now unused function definition, its now
> empty header, and all includes of this header.
>
> Fixes: 3a236f6a5cf2 ("dma: contiguous: Turn heap registration logic around")
> Reported-by: Mark Brown <broonie@kernel.org>
> Closes: https://lore.kernel.org/linux-next/acbjaDJ1a-YQC64d@sirena.co.uk/
> Signed-off-by: Maxime Ripard <mripard@kernel.org>
> ---
>  drivers/dma-buf/heaps/cma_heap.c  |  1 -
>  include/linux/dma-buf/heaps/cma.h | 16 ----------------
>  kernel/dma/contiguous.c           |  5 -----
>  3 files changed, 22 deletions(-)
>
> diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
> index f8a3d87f3ccee9630383ba28502eb40b10671cc2..cc517ac68a0bec0788abcb338c03f530d169013b 100644
> --- a/drivers/dma-buf/heaps/cma_heap.c
> +++ b/drivers/dma-buf/heaps/cma_heap.c
> @@ -12,11 +12,10 @@
>  
>  #define pr_fmt(fmt) "cma_heap: " fmt
>  
>  #include <linux/cma.h>
>  #include <linux/dma-buf.h>
> -#include <linux/dma-buf/heaps/cma.h>
>  #include <linux/dma-heap.h>
>  #include <linux/dma-map-ops.h>
>  #include <linux/err.h>
>  #include <linux/highmem.h>
>  #include <linux/io.h>
> diff --git a/include/linux/dma-buf/heaps/cma.h b/include/linux/dma-buf/heaps/cma.h
> deleted file mode 100644
> index e751479e21e703e24a5f799b4a7fc8bd0df3c1c4..0000000000000000000000000000000000000000
> --- a/include/linux/dma-buf/heaps/cma.h
> +++ /dev/null
> @@ -1,16 +0,0 @@
> -/* SPDX-License-Identifier: GPL-2.0 */
> -#ifndef DMA_BUF_HEAP_CMA_H_
> -#define DMA_BUF_HEAP_CMA_H_
> -
> -struct cma;
> -
> -#ifdef CONFIG_DMABUF_HEAPS_CMA
> -int dma_heap_cma_register_heap(struct cma *cma);
> -#else
> -static inline int dma_heap_cma_register_heap(struct cma *cma)
> -{
> -	return 0;
> -}
> -#endif // CONFIG_DMABUF_HEAPS_CMA
> -
> -#endif // DMA_BUF_HEAP_CMA_H_
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index ad50512d71d3088a73e4b1ac02d6e6122374888e..9fe001c712339f8388d3f40cca3dfff3f707fcbf 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -40,11 +40,10 @@
>  #include <asm/page.h>
>  
>  #include <linux/memblock.h>
>  #include <linux/err.h>
>  #include <linux/sizes.h>
> -#include <linux/dma-buf/heaps/cma.h>
>  #include <linux/dma-map-ops.h>
>  #include <linux/cma.h>
>  #include <linux/nospec.h>
>  
>  #ifdef CONFIG_CMA_SIZE_MBYTES
> @@ -270,14 +269,10 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
>  						  selected_limit,
>  						  &dma_contiguous_default_area,
>  						  fixed);
>  		if (ret)
>  			return;
> -
> -		ret = dma_heap_cma_register_heap(dma_contiguous_default_area);
> -		if (ret)
> -			pr_warn("Couldn't register default CMA heap.");
After this change no dma-buf heap for the default CMA area is created if it has 
not been specified in device-tree. This might be especially a problem for the
non-dt systems.


>  	}
>  }
>  
>  void __weak
>  dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
>
>
Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland