From nobody Tue Apr 7 20:07:31 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1E93E17B506; Fri, 27 Feb 2026 13:23:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772198600; cv=none; b=O5vjEfBBT8dLU//s31QT4feuPlb8QPQJQ0I2dNpT3rILIGzxTTu2e7lVyQo8rnNwsFJoDnKECEksnzq/JQg+12NwETOZCJFx9N6VyrV1jUM9Tx+Po7mJG3RaHIzlbPhpbuwzCufLjLlk1or+Z0fpNSX6/y9A463Gk9B5U7sOKmY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772198600; c=relaxed/simple; bh=3nkigmqj26MiaB2hrjIoaEchPKanWq9PIyuPV01pGW4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=qVzB1O40daiD1zLDfwBjZMmeQYQ3FNNwAYCs+U+vot7B2sTt7sGQXLh/jxDrNoNbbOfXDtvhqnW088Ey+hpVUwVb3RNk4VN3EGypThDZXbfvM9QAPzRd3AmQdtZmNY4RvE43jbDyxxPF7/07/rnbKM5bCqrQkC8IP3YvnwKpiKI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ep8QG9Jw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ep8QG9Jw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37B44C116C6; Fri, 27 Feb 2026 13:23:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772198599; bh=3nkigmqj26MiaB2hrjIoaEchPKanWq9PIyuPV01pGW4=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ep8QG9JwZhst67AO+YrR9CD7vN8a2Q0/SvF7GjJ1AJRdN8amF6qrQtsrtjsPM/os6 jq7h6SKaZVSq5kQ5Dk2OtQd6WOoxu2LglQkpe/IhJU+F3cnv+UJagUHeQJbBWjIQJs pChxUqUVVnx1ScPP1DP5WrsSfsdnqkx72VuU6Wg61+v95Kq6RLudN19qlT2IPxo2Ik PHDT+ZaIgIKjUBVWQcplwELu089x8mY0Uyp4sDIOAVavKrqNaY11takn6c0DB4u0QC fkwXmDwZzDAz3yXJtDegrVMxOTeGBoNmjm3PqZfod981ExtPO75+qEv7WO+vM+oFho 54Mh8NCxGaBMg== From: Maxime Ripard Date: Fri, 27 Feb 2026 14:15:40 +0100 Subject: [PATCH v2 1/9] dma: contiguous: Turn heap registration logic around Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260227-dma-buf-heaps-as-modules-v2-1-454aee7e06cc@kernel.org> References: <20260227-dma-buf-heaps-as-modules-v2-0-454aee7e06cc@kernel.org> In-Reply-To: <20260227-dma-buf-heaps-as-modules-v2-0-454aee7e06cc@kernel.org> To: Sumit Semwal , Benjamin Gaignard , Brian Starkey , John Stultz , "T.J. Mercier" , =?utf-8?q?Christian_K=C3=B6nig?= , Marek Szyprowski , Robin Murphy , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Cc: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-mm@kvack.org, Maxime Ripard X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=5155; i=mripard@kernel.org; h=from:subject:message-id; bh=3nkigmqj26MiaB2hrjIoaEchPKanWq9PIyuPV01pGW4=; b=owGbwMvMwCmsHn9OcpHtvjLG02pJDJkLZ+14wCSwWetCxePNRjzWT5eynlx0u+Kw4t+kD43v7 He/7/B82TGVhUGYk0FWTJHliUzY6eXti6sc7Ff+gJnDygQyhIGLUwAmIvKTsYbzdlm6p7+41j7e BBOeHHN9vveOL0Q1TjqnxTQF5Rv53HxdmZC5p8zML/1tkwPrg9JCxlpJQeG512WDL054qdxWaxf lNNVAZPGFk7kqB46k50zUPr9kvu9Jpry8bYI9dyZc3s8u/BcA X-Developer-Key: i=mripard@kernel.org; a=openpgp; fpr=BE5675C37E818C8B5764241C254BCFC56BF6CE8D The CMA heap instantiation was initially developed by having the contiguous DMA code call into the CMA heap to create a new instance every time a reserved memory area is probed. Turning the CMA heap into a module would create a dependency of the kernel on a module, which doesn't work. Let's turn the logic around and do the opposite: store all the reserved memory CMA regions into the contiguous DMA code, and provide an iterator for the heap to use when it probes. Reviewed-by: T.J. Mercier Signed-off-by: Maxime Ripard Reviewed-by: Albert Esteve --- drivers/dma-buf/heaps/cma_heap.c | 18 ++---------------- include/linux/dma-map-ops.h | 5 +++++ kernel/dma/contiguous.c | 26 ++++++++++++++++++++++++-- 3 files changed, 31 insertions(+), 18 deletions(-) diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_h= eap.c index bd3370b9a3f6d4e18885a1d0e8ba3f659b85ef47..f8a3d87f3ccee9630383ba28502= eb40b10671cc2 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -28,23 +28,10 @@ #include #include =20 #define DEFAULT_CMA_NAME "default_cma_region" =20 -static struct cma *dma_areas[MAX_CMA_AREAS] __initdata; -static unsigned int dma_areas_num __initdata; - -int __init dma_heap_cma_register_heap(struct cma *cma) -{ - if (dma_areas_num >=3D ARRAY_SIZE(dma_areas)) - return -EINVAL; - - dma_areas[dma_areas_num++] =3D cma; - - return 0; -} - struct cma_heap { struct dma_heap *heap; struct cma *cma; }; =20 @@ -412,22 +399,21 @@ static int __init __add_cma_heap(struct cma *cma, con= st char *name) } =20 static int __init add_cma_heaps(void) { struct cma *default_cma =3D dev_get_cma_area(NULL); + struct cma *cma; unsigned int i; int ret; =20 if (default_cma) { ret =3D __add_cma_heap(default_cma, DEFAULT_CMA_NAME); if (ret) return ret; } =20 - for (i =3D 0; i < dma_areas_num; i++) { - struct cma *cma =3D dma_areas[i]; - + for (i =3D 0; (cma =3D dma_contiguous_get_reserved_region(i)) !=3D NULL; = i++) { ret =3D __add_cma_heap(cma, cma_get_name(cma)); if (ret) { pr_warn("Failed to add CMA heap %s", cma_get_name(cma)); continue; } diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h index 60b63756df821d839436618f1fca2bfa3eabe075..3007c68a8ec5b85990d1938d04a= 2f05c1a71acdb 100644 --- a/include/linux/dma-map-ops.h +++ b/include/linux/dma-map-ops.h @@ -110,10 +110,11 @@ bool dma_release_from_contiguous(struct device *dev, = struct page *pages, int count); struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t g= fp); void dma_free_contiguous(struct device *dev, struct page *page, size_t siz= e); =20 void dma_contiguous_early_fixup(phys_addr_t base, unsigned long size); +struct cma *dma_contiguous_get_reserved_region(unsigned int idx); #else /* CONFIG_DMA_CMA */ static inline struct cma *dev_get_cma_area(struct device *dev) { return NULL; } @@ -148,10 +149,14 @@ static inline void dma_free_contiguous(struct device = *dev, struct page *page, __free_pages(page, get_order(size)); } static inline void dma_contiguous_early_fixup(phys_addr_t base, unsigned l= ong size) { } +static inline struct cma *dma_contiguous_get_reserved_region(unsigned int = idx) +{ + return NULL; +} #endif /* CONFIG_DMA_CMA*/ =20 #ifdef CONFIG_DMA_DECLARE_COHERENT int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, dma_addr_t device_addr, size_t size); diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index c56004d314dc2e436cddf3b20a4ee6ce8178bee4..14bd54fb758537f01a6fe27318e= 7b683964e20b1 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -456,10 +456,32 @@ void dma_free_contiguous(struct device *dev, struct p= age *page, size_t size) #include =20 #undef pr_fmt #define pr_fmt(fmt) fmt =20 +static struct cma *rmem_cma_areas[MAX_CMA_AREAS]; +static unsigned int rmem_cma_areas_num; + +static int rmem_cma_insert_area(struct cma *cma) +{ + if (rmem_cma_areas_num >=3D ARRAY_SIZE(rmem_cma_areas)) + return -EINVAL; + + rmem_cma_areas[rmem_cma_areas_num++] =3D cma; + + return 0; +} + +struct cma *dma_contiguous_get_reserved_region(unsigned int idx) +{ + if (idx >=3D rmem_cma_areas_num) + return NULL; + + return rmem_cma_areas[idx]; +} +EXPORT_SYMBOL_GPL(dma_contiguous_get_reserved_region); + static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *= dev) { dev->cma_area =3D rmem->priv; return 0; } @@ -504,13 +526,13 @@ static int __init rmem_cma_setup(struct reserved_mem = *rmem) rmem->priv =3D cma; =20 pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n", &rmem->base, (unsigned long)rmem->size / SZ_1M); =20 - err =3D dma_heap_cma_register_heap(cma); + err =3D rmem_cma_insert_area(cma); if (err) - pr_warn("Couldn't register CMA heap."); + pr_warn("Couldn't store CMA reserved area."); =20 return 0; } RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup); #endif --=20 2.53.0