linux-kernel - [PATCH v8 4/5] dma: contiguous: Reserve default CMA heap

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Message-Id: <20251013-dma-buf-ecc-heap-v8-4-04ce150ea3d9@kernel.org>
Date: Mon, 13 Oct 2025 10:35:19 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Sumit Semwal <sumit.semwal@...aro.org>, 
 Benjamin Gaignard <benjamin.gaignard@...labora.com>, 
 Brian Starkey <Brian.Starkey@....com>, John Stultz <jstultz@...gle.com>, 
 "T.J. Mercier" <tjmercier@...gle.com>, Jonathan Corbet <corbet@....net>, 
 Christian König <christian.koenig@....com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Robin Murphy <robin.murphy@....com>
Cc: Andrew Davis <afd@...com>, Jared Kangas <jkangas@...hat.com>, 
 Mattijs Korpershoek <mkorpershoek@...nel.org>, linux-media@...r.kernel.org, 
 dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org, 
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
 iommu@...ts.linux.dev, Maxime Ripard <mripard@...nel.org>
Subject: [PATCH v8 4/5] dma: contiguous: Reserve default CMA heap

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 <tjmercier@...gle.com>
Signed-off-by: Maxime Ripard <mripard@...nel.org>
---
 kernel/dma/contiguous.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index d67e95094749d45f43c1809c175e491a3f55b2e1..d8fd6f779f797f711b8e0fd628f868d644b8f784 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -240,17 +240,23 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
 		selected_size = max(size_bytes, cma_early_percent_memory());
 #endif
 	}

 	if (selected_size && !dma_contiguous_default_area) {
+		int ret;
+
 		pr_debug("%s: reserving %ld MiB for global area\n", __func__,
 			 (unsigned long)selected_size / SZ_1M);

 		dma_contiguous_reserve_area(selected_size, selected_base,
 					    selected_limit,
 					    &dma_contiguous_default_area,
 					    fixed);
+
+		ret = dma_heap_cma_register_heap(dma_contiguous_default_area);
+		if (ret)
+			pr_warn("Couldn't register default CMA heap.");
 	}
 }

 void __weak
 dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)

-- 
2.51.0