linux-toradex.git/kernel/dma/contiguous.c, branch v6.19-rc2

dma: contiguous: Reserve default CMA heap

2025-10-18T16:01:21+00:00

The CMA code, in addition to the reserved-memory regions in the device
tree, will also register a default CMA region if the device tree doesn't
provide any, with its size and position coming from either the kernel
command-line or configuration.

Let's register that one for use to create a heap for it.

Reviewed-by: T.J. Mercier 
Signed-off-by: Maxime Ripard 
Acked-by: Marek Szyprowski 
Signed-off-by: Sumit Semwal 
Link: https://lore.kernel.org/r/20251013-dma-buf-ecc-heap-v8-4-04ce150ea3d9@kernel.org

dma: contiguous: Register reusable CMA regions at boot

2025-10-18T16:01:21+00:00

In order to create a CMA dma-buf heap instance for each CMA heap region
in the system, we need to collect all of them during boot.

They are created from two main sources: the reserved-memory regions in
the device tree, and the default CMA region created from the
configuration or command line parameters, if no default region is
provided in the device tree.

Let's collect all the device-tree defined CMA regions flagged as
reusable.

Reviewed-by: T.J. Mercier 
Signed-off-by: Maxime Ripard 
Acked-by: Marek Szyprowski 
Signed-off-by: Sumit Semwal 
Link: https://lore.kernel.org/r/20251013-dma-buf-ecc-heap-v8-3-04ce150ea3d9@kernel.org

of: reserved_mem: Restructure call site for dma_contiguous_early_fixup()

2025-08-11T11:05:38+00:00

Restructure the call site for dma_contiguous_early_fixup() to
where the reserved_mem nodes are being parsed from the DT so that
dma_mmu_remap[] is populated before dma_contiguous_remap() is called.

Fixes: 8a6e02d0c00e ("of: reserved_mem: Restructure how the reserved memory regions are processed")
Signed-off-by: Oreoluwa Babatunde 
Tested-by: William Zhang 
Signed-off-by: Marek Szyprowski 
Link: https://lore.kernel.org/r/20250806172421.2748302-1-oreoluwa.babatunde@oss.qualcomm.com

dma-contiguous: hornor the cma address limit setup by user

2025-06-12T06:38:40+00:00

When porting a cma related usage from x86_64 server to arm64 server,
the "cma=4G@4G" setup failed on arm64. The reason is arm64 and some
other architectures have specific physical address limit for reserved
cma area, like 4GB due to the device's need for 32 bit dma. Actually
lots of platforms of those architectures don't have this device dma
limit, but still have to obey it, and are not able to reserve a huge
cma pool.

This situation could be improved by honoring the user input cma
physical address than the arch limit. As when users specify it, they
already knows what the default is which probably can't suit them.

Suggested-by: Robin Murphy 
Signed-off-by: Feng Tang 
Signed-off-by: Marek Szyprowski 
Link: https://lore.kernel.org/r/20250612021417.44929-1-feng.tang@linux.alibaba.com

dma/contiguous: avoid warning about unused size_bytes

2025-04-09T15:28:53+00:00

When building with W=1, this variable is unused for configs with
CONFIG_CMA_SIZE_SEL_PERCENTAGE=y:

kernel/dma/contiguous.c:67:26: error: 'size_bytes' defined but not used [-Werror=unused-const-variable=]

Change this to a macro to avoid the warning.

Fixes: c64be2bb1c6e ("drivers: add Contiguous Memory Allocator")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Marek Szyprowski 
Link: https://lore.kernel.org/r/20250409151557.3890443-1-arnd@kernel.org

mm/cma: drop CONFIG_CMA_DEBUG

2024-02-22T18:24:53+00:00

All pr_debug() prints in (mm/cma.c) could be enabled via standard Makefile
based method.  Besides cma_debug_show_areas() should always be called
during cma_alloc() failure path.  This seemingly redundant config,
CONFIG_CMA_DEBUG can be dropped without any problem.

[lukas.bulwahn@gmail.com: remove debug code to removed CONFIG_CMA_DEBUG]
  Link: https://lkml.kernel.org/r/20240207143825.986-1-lukas.bulwahn@gmail.com
Link: https://lkml.kernel.org/r/20240205031647.283510-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Signed-off-by: Lukas Bulwahn 
Cc: Christoph Hellwig 
Cc: Marek Szyprowski 
Cc: Robin Murphy 
Signed-off-by: Andrew Morton

Revert "dma-contiguous: check for memory region overlap"

2023-09-08T08:58:32+00:00

This reverts commit 3fa6456ebe13adab3ba1817c8e515a5b88f95dce.

The Commit broke the CMA region creation through DT on arm64,
as showed below logs with "memblock=debug":
[    0.000000] memblock_phys_alloc_range: 41943040 bytes align=0x200000
from=0x0000000000000000 max_addr=0x00000000ffffffff
early_init_dt_alloc_reserved_memory_arch+0x34/0xa0
[    0.000000] memblock_reserve: [0x00000000fd600000-0x00000000ffdfffff]
memblock_alloc_range_nid+0xc0/0x19c
[    0.000000] Reserved memory: overlap with other memblock reserved region

>From call flow, region we defined in DT was always reserved before entering
into rmem_cma_setup. Also, rmem_cma_setup has one routine cma_init_reserved_mem
to ensure the region was reserved. Checking the region not reserved here seems
not correct.

early_init_fdt_scan_reserved_mem:
    fdt_scan_reserved_mem
        __reserved_mem_reserve_reg
		early_init_dt_reserve_memory
			memblock_reserve(using “reg” prop case)
        fdt_init_reserved_mem
		__reserved_mem_alloc_size
			*early_init_dt_alloc_reserved_memory_arch*
				memblock_reserve(dynamic alloc case)
        __reserved_mem_init_node
		rmem_cma_setup(region overlap check here should always fail)

Example DT can be used to reproduce issue:

    dump_mem: mem_dump_region {
            compatible = "shared-dma-pool";
            alloc-ranges = <0x0 0x00000000 0x0 0xffffffff>;
            reusable;
            size = <0 0x2800000>;
    };

Signed-off-by: Zhenhua Huang

dma-contiguous: check for memory region overlap

2023-07-31T15:54:56+00:00

In the process of parsing the DTS, check whether the memory region
specified by the DTS CMA node area overlaps with the kernel text
memory space reserved by memblock before calling
early_init_fdt_scan_reserved_mem.

Signed-off-by: Binglei Wang 
Signed-off-by: Christoph Hellwig

dma-contiguous: support numa CMA for specified node

2023-07-31T15:54:29+00:00

The kernel parameter 'cma_pernuma=' only supports reserving the same
size of CMA area for each node. We need to reserve different sizes of
CMA area for specified nodes if these devices belong to different nodes.

Adding another kernel parameter 'numa_cma=' to reserve CMA area for
the specified node. If we want to use one of these parameters, we need to
enable DMA_NUMA_CMA.

At the same time, print the node id in cma_declare_contiguous_nid() if
CONFIG_NUMA is enabled.

Signed-off-by: Yajun Deng 
Signed-off-by: Christoph Hellwig

dma-contiguous: support per-numa CMA for all architectures

2023-07-31T15:54:28+00:00

In the commit b7176c261cdb ("dma-contiguous: provide the ability to
reserve per-numa CMA"), Barry adds DMA_PERNUMA_CMA for ARM64.

But this feature is architecture independent, so support per-numa CMA
for all architectures, and enable it by default if NUMA.

Signed-off-by: Yajun Deng 
Tested-by: Yicong Yang 
Signed-off-by: Christoph Hellwig