linux-kernel - [PATCH v3] of: reserved_mem: Restructure call site for dma_contiguous_early

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Message-Id: <20250730002956.1812694-1-oreoluwa.babatunde@oss.qualcomm.com>
Date: Tue, 29 Jul 2025 17:29:56 -0700
From: Oreoluwa Babatunde <oreoluwa.babatunde@....qualcomm.com>
To: robh@...nel.org, m.szyprowski@...sung.com, robin.murphy@....com
Cc: saravanak@...gle.com, quic_obabatun@...cinc.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux.dev, william.zhang@...adcom.com,
        kernel@....qualcomm.com, will@...nel.org, djakov@...nel.org,
        Oreoluwa Babatunde <oreoluwa.babatunde@....qualcomm.com>
Subject: [PATCH v3] 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@....qualcomm.com>
Tested-by: William Zhang <william.zhang@...adcom.com>
---
v3: Wrap the call to dma_contiguous_early_fixup() with a check for
    CONFIG_DMA_CMA to fix compile error seen on x86. The __weak function
    definition introduced in v2 was not sufficient to prevent the issue,
    so remove that as well.
    Also add Tested-by tag from William Zhang.

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 | 20 ++++++++++++++++----
 kernel/dma/contiguous.c      |  2 --
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 77016c0cc296..cfffecb91c3a 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"
 
@@ -175,13 +176,19 @@ 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. */
+#ifdef CONFIG_DMA_CMA
+			if (of_flat_dt_is_compatible(node, "shared-dma-pool") &&
+			    of_get_flat_dt_prop(node, "reusable", NULL))
+				dma_contiguous_early_fixup(base, size);
+#endif
 			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;
 	}
@@ -472,7 +479,12 @@ static int __init __reserved_mem_alloc_size(unsigned long node, const char *unam
 		       uname, (unsigned long)(size / SZ_1M));
 		return -ENOMEM;
 	}
-
+#ifdef CONFIG_DMA_CMA
+	/* 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);
+#endif
 	/* Save region in the reserved_mem array */
 	fdt_reserved_mem_save_node(node, uname, base, size);
 	return 0;
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