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libcamera: prefer udmabuf over dma-heaps #464

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libcamera: prefer udmabuf over dma-heaps #464

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41 changes: 41 additions & 0 deletions ...media/libcamera/libcamera/0001-libcamera-dma_buf_allocator-Prefer-udmabuf-over-dma-.patch
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Original file line number Diff line number Diff line change
@@ -0,0 +1,41 @@
From 49d57827bc17e4816315a4836eb44212f7597c9c Mon Sep 17 00:00:00 2001
From: Wenmeng Liu <wenmeng.liu@oss.qualcomm.com>
Date: Thu, 10 Sep 2026 12:22:08 +0800
Subject: [PATCH] libcamera: dma_buf_allocator: Prefer udmabuf over dma-heaps

Reorder the provider list so that /dev/udmabuf is tried before the
CMA and system dma-heaps. Components that allow the udmabuf provider
(software ISP, virtual pipeline) now use it whenever /dev/udmabuf is
available, instead of falling back to it only when the dma-heaps can
not be opened.

Signed-off-by: Wenmeng Liu <wenmeng.liu@oss.qualcomm.com>
Upstream-Status: Pending
---
src/libcamera/dma_buf_allocator.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp
index d8c62dd67..a18e6d7a5 100644
--- a/src/libcamera/dma_buf_allocator.cpp
+++ b/src/libcamera/dma_buf_allocator.cpp
@@ -41,6 +41,8 @@ struct DmaBufAllocatorInfo {
#endif

static constexpr std::array<DmaBufAllocatorInfo, 4> providerInfos = { {
+ /* Prefer udmabuf over the dma-heaps. */
+ { DmaBufAllocator::DmaBufAllocatorFlag::UDmaBuf, "/dev/udmabuf" },
/*
* /dev/dma_heap/linux,cma is the CMA dma-heap. When the cma heap size is
* specified on the kernel command line, this gets renamed to "reserved".
@@ -48,7 +50,6 @@ static constexpr std::array<DmaBufAllocatorInfo, 4> providerInfos = { {
{ DmaBufAllocator::DmaBufAllocatorFlag::CmaHeap, "/dev/dma_heap/linux,cma" },
{ DmaBufAllocator::DmaBufAllocatorFlag::CmaHeap, "/dev/dma_heap/reserved" },
{ DmaBufAllocator::DmaBufAllocatorFlag::SystemHeap, "/dev/dma_heap/system" },
- { DmaBufAllocator::DmaBufAllocatorFlag::UDmaBuf, "/dev/udmabuf" },
} };

LOG_DEFINE_CATEGORY(DmaBufAllocator)
--
2.34.1

6 changes: 6 additions & 0 deletions recipes-multimedia/libcamera/libcamera_%.bbappend
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@@ -1 +1,7 @@
PACKAGECONFIG:append:qcom-distro = " gst"

FILESEXTRAPATHS:prepend:qcom := "${THISDIR}/${BPN}:"

SRC_URI:append:qcom = " \
file://0001-libcamera-dma_buf_allocator-Prefer-udmabuf-over-dma-.patch \
"
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