RE: [PATCH v2] of: reserved_mem: Restructure call site for dma_contiguous_early_fixup()

[William Zhang]

> -----Original Message-----
> From: Oreoluwa Babatunde <oreoluwa.babatunde@xxxxxxxxxxxxxxxx>
> Sent: Friday, July 18, 2025 4:45 PM
> To: robh@xxxxxxxxxx; m.szyprowski@xxxxxxxxxxx; robin.murphy@xxxxxxx
> Cc: saravanak@xxxxxxxxxx; quic_obabatun@xxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> iommu@xxxxxxxxxxxxxxx; william.zhang@xxxxxxxxxxxx;
> kernel@xxxxxxxxxxxxxxxx; will@xxxxxxxxxx; djakov@xxxxxxxxxx; Oreoluwa
> Babatunde <oreoluwa.babatunde@xxxxxxxxxxxxxxxx>
> Subject: [PATCH v2] of: reserved_mem: Restructure call site for
> dma_contiguous_early_fixup()
>
> 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
> <oreoluwa.babatunde@xxxxxxxxxxxxxxxx>
> ---
> v2: Add a check for the "reusable" property to narrow things down to
>     only cma regions.
>     Also add __weak function definition for dma_contiguous_early_fixup()
>     to avoid compile errors on architectures that do not define the
>     function.
>
>  drivers/of/of_reserved_mem.c | 21 ++++++++++++++++++---
>  kernel/dma/contiguous.c      |  2 --
>  2 files changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 77016c0cc296..eee96172883a 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -25,6 +25,7 @@
>  #include <linux/memblock.h>
>  #include <linux/kmemleak.h>
>  #include <linux/cma.h>
> +#include <linux/dma-map-ops.h>
>
>  #include "of_private.h"
>
> @@ -147,6 +148,11 @@ static int __init
> early_init_dt_reserve_memory(phys_addr_t base,
>  	return memblock_reserve(base, size);
>  }
>
> +void __weak
> +dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
> +{
> +}
> +
>  /*
>   * __reserved_mem_reserve_reg() - reserve all memory described in 'reg'
> property
>   */
> @@ -175,13 +181,18 @@ static int __init
> __reserved_mem_reserve_reg(unsigned long node,
>  		base = dt_mem_next_cell(dt_root_addr_cells, &prop);
>  		size = dt_mem_next_cell(dt_root_size_cells, &prop);
>
> -		if (size &&
> -		    early_init_dt_reserve_memory(base, size, nomap) == 0)
> +		if (size && early_init_dt_reserve_memory(base, size,
nomap)
> == 0) {
> +			/* Architecture specific contiguous memory fixup.
*/
> +			if (of_flat_dt_is_compatible(node,
"shared-dma-pool")
> &&
> +			    of_get_flat_dt_prop(node, "reusable", NULL))
> +				dma_contiguous_early_fixup(base, size);
> +
>  			pr_debug("Reserved memory: reserved region for
node
> '%s': base %pa, size %lu MiB\n",
>  				uname, &base, (unsigned long)(size /
SZ_1M));
> -		else
> +		} else {
>  			pr_err("Reserved memory: failed to reserve memory
> for node '%s': base %pa, size %lu MiB\n",
>  			       uname, &base, (unsigned long)(size /
SZ_1M));
> +		}
>
>  		len -= t_len;
>  	}
> @@ -472,6 +483,10 @@ static int __init
> __reserved_mem_alloc_size(unsigned long node, const char *unam
>  		       uname, (unsigned long)(size / SZ_1M));
>  		return -ENOMEM;
>  	}
> +	/* Architecture specific contiguous memory fixup. */
> +	if (of_flat_dt_is_compatible(node, "shared-dma-pool") &&
> +	    of_get_flat_dt_prop(node, "reusable", NULL))
> +		dma_contiguous_early_fixup(base, size);
>
>  	/* Save region in the reserved_mem array */
>  	fdt_reserved_mem_save_node(node, uname, base, size);
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index 67af8a55185d..d9b9dcba6ff7 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -483,8 +483,6 @@ static int __init rmem_cma_setup(struct
> reserved_mem *rmem)
>  		pr_err("Reserved memory: unable to setup CMA region\n");
>  		return err;
>  	}
> -	/* Architecture specific contiguous memory fixup. */
> -	dma_contiguous_early_fixup(rmem->base, rmem->size);
>
>  	if (default_cma)
>  		dma_contiguous_default_area = cma;
> --
> 2.34.1

Tested-by: William Zhang <william.zhang@xxxxxxxxxxxx>

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