[{"id":37422,"web_url":"https://patchwork.libcamera.org/comment/37422/","msgid":"","date":"2025-12-17T10:30:32","subject":"Re: [PATCH v9 01/26] libcamera: software_isp: gbm: Add a GBM helper\n\tclass for GPU surface access","submitter":{"id":140,"url":"https://patchwork.libcamera.org/api/people/140/","name":"Robert Mader","email":"robert.mader@collabora.com"},"content":"We might want switch away from the GBM platform in a follow-up. For now:\n\nReviewed-by: Robert Mader \n\nOn 17.12.25 11:01, Bryan O'Donoghue wrote:\n> A helper class to interact with GBM. This will allow us to specify the\n> internal storage format of the GPU when making a texture for the Debayer\n> vertex/fragment shaders and thus ensure we receive an uncompressed and\n> untiled output buffer.\n>\n> Acked-by: Kieran Bingham \n> Reviewed-by: Milan Zamazal \n> Signed-off-by: Bryan O'Donoghue \n> ---\n> include/libcamera/internal/gbm.h | 39 ++++++++\n> include/libcamera/internal/meson.build | 1 +\n> src/libcamera/gbm.cpp | 130 +++++++++++++++++++++++++\n> src/libcamera/meson.build | 10 ++\n> 4 files changed, 180 insertions(+)\n> create mode 100644 include/libcamera/internal/gbm.h\n> create mode 100644 src/libcamera/gbm.cpp\n>\n> diff --git a/include/libcamera/internal/gbm.h b/include/libcamera/internal/gbm.h\n> new file mode 100644\n> index 000000000..09811d1ef\n> --- /dev/null\n> +++ b/include/libcamera/internal/gbm.h\n> @@ -0,0 +1,39 @@\n> +/* SPDX-License-Identifier: LGPL-2.1-or-later */\n> +/*\n> + * Copyright (C) 2024, Linaro Ltd.\n> + *\n> + * Authors:\n> + * Bryan O'Donoghue \n> + *\n> + * Helper class for managing GBM interactions\n> + */\n> +\n> +#pragma once\n> +\n> +#include \n> +\n> +#include \n> +\n> +#include \n> +\n> +namespace libcamera {\n> +\n> +LOG_DECLARE_CATEGORY(GBM)\n> +\n> +class GBM\n> +{\n> +public:\n> +\tGBM();\n> +\t~GBM();\n> +\n> +\tint createDevice();\n> +\tstruct gbm_device *getDevice();\n> +\tPixelFormat getPixelFormat();\n> +\n> +private:\n> +\tint fd_;\n> +\tstruct gbm_device *gbmDevice_;\n> +\tPixelFormat format_;\n> +};\n> +\n> +} /* namespace libcamera */\n> diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build\n> index e9540a2f7..b8324996b 100644\n> --- a/include/libcamera/internal/meson.build\n> +++ b/include/libcamera/internal/meson.build\n> @@ -23,6 +23,7 @@ libcamera_internal_headers = files([\n> 'dma_buf_allocator.h',\n> 'formats.h',\n> 'framebuffer.h',\n> + 'gbm.h',\n> 'global_configuration.h',\n> 'ipa_data_serializer.h',\n> 'ipa_manager.h',\n> diff --git a/src/libcamera/gbm.cpp b/src/libcamera/gbm.cpp\n> new file mode 100644\n> index 000000000..659860500\n> --- /dev/null\n> +++ b/src/libcamera/gbm.cpp\n> @@ -0,0 +1,130 @@\n> +/* SPDX-License-Identifier: LGPL-2.1-or-later */\n> +/*\n> + * Copyright (C) 2024, Linaro Ltd.\n> + *\n> + * Authors:\n> + * Bryan O'Donoghue \n> + *\n> + * Helper class for managing GBM interactions\n> + */\n> +\n> +#include \"libcamera/internal/gbm.h\"\n> +\n> +#include \n> +#include \n> +#include \n> +#include \n> +#include \n> +\n> +#include \n> +#include \n> +\n> +namespace libcamera {\n> +\n> +LOG_DEFINE_CATEGORY(GBM)\n> +\n> +/**\n> + * \\class GBM\n> + * \\brief Helper class for managing GBM interactions\n> + *\n> + * The GBM class provides a simplified interface for creating and managing\n> + * GBM devices. It handles the initialization and teardown of GBM devices\n> + * used for buffer allocation in graphics and camera pipelines.\n> + *\n> + * This class is responsible for opening a DRI render node, creating a GBM\n> + * device, and providing access to the device and its associated pixel format.\n> + */\n> +\n> +/**\n> + *\\var GBM::fd_\n> + *\\brief file descriptor to DRI device\n> + */\n> +\n> +/**\n> + *\\var GBM::gbmDevice_\n> + *\\brief Pointer to GBM device structure derived from fd_\n> + */\n> +\n> +/**\n> + *\\var GBM::format_\n> + *\\brief Pixel format the GBM surface was created in\n> + */\n> +\n> +/**\n> + *\\brief GBM constructor.\n> + *\n> + * Creates a GBM instance with unitialised state.\n> + */\n> +GBM::GBM()\n> +{\n> +\tfd_ = 0;\n> +\tgbmDevice_ = nullptr;\n> +}\n> +\n> +/**\n> + *\\brief GBM destructor\n> + *\n> + * Cleans up the GBM device if it was successfully created, and closes\n> + * the associated file descriptor.\n> + */\n> +GBM::~GBM()\n> +{\n> +\tif (gbmDevice_)\n> +\t\tgbm_device_destroy(gbmDevice_);\n> +}\n> +\n> +/**\n> + * \\brief Create and initialize a GBM device\n> + *\n> + * \\todo Get dri device name from envOption setting\n> + *\n> + * Opens the DRI render node (/dev/dri/renderD128) and creates a GBM\n> + * device using the libgbm library. Sets the default pixel format to\n> + * ARGB8888.\n> + *\n> + * \\return 0 on success, or a negative error code on failure\n> + */\n> +int GBM::createDevice()\n> +{\n> +\tconst char *dri_node = \"/dev/dri/renderD128\";\n> +\n> +\tfd_ = open(dri_node, O_RDWR | O_CLOEXEC);\n> +\tif (fd_ < 0) {\n> +\t\tLOG(GBM, Error) << \"Open \" << dri_node << \" fail \" << fd_;\n> +\t\treturn fd_;\n> +\t}\n> +\n> +\tgbmDevice_ = gbm_create_device(fd_);\n> +\tif (!gbmDevice_) {\n> +\t\tLOG(GBM, Error) << \"gbm_create_device fail\";\n> +\t\tclose(fd_);\n> +\t\treturn -errno;\n> +\t}\n> +\n> +\tformat_ = libcamera::formats::ARGB8888;\n> +\n> +\treturn 0;\n> +}\n> +\n> +/**\n> + * \\brief Retrieve the GBM device handle\n> + *\n> + * \\return Pointer to the gbm_device structure, or nullptr if the device\n> + * has not been created\n> + */\n> +struct gbm_device *GBM::getDevice()\n> +{\n> +\treturn gbmDevice_;\n> +}\n> +\n> +/**\n> + * \\brief Retrieve the pixel format\n> + *\n> + * \\return The PixelFormat used by this GBM instance (ARGB8888)\n> + */\n> +\n> +PixelFormat GBM::getPixelFormat()\n> +{\n> +\treturn format_;\n> +}\n> +} /* namespace libcamera */\n> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build\n> index 575408b2c..e5b5330a8 100644\n> --- a/src/libcamera/meson.build\n> +++ b/src/libcamera/meson.build\n> @@ -70,6 +70,15 @@ libcamera_deps = []\n> libatomic = cc.find_library('atomic', required : false)\n> libthreads = dependency('threads')\n> \n> +libgbm = cc.find_library('gbm', required: false)\n> +gbm_works = cc.check_header('gbm.h', required: false)\n> +\n> +if libgbm.found() and gbm_works\n> + libcamera_internal_sources += files([\n> + 'gbm.cpp',\n> + ])\n> +endif\n> +\n> subdir('base')\n> subdir('converter')\n> subdir('ipa')\n> @@ -178,6 +187,7 @@ libcamera_deps += [\n> libcamera_base_private,\n> libcrypto,\n> libdl,\n> + libgbm,\n> liblttng,\n> libudev,\n> libyaml,","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id A2A07C3257\n\tfor ;\n\tWed, 17 Dec 2025 10:30:41 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 52F5961A5B;\n\tWed, 17 Dec 2025 11:30:41 +0100 (CET)","from sender4-op-o12.zoho.com (sender4-op-o12.zoho.com\n\t[136.143.188.12])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 2E7D961A2C\n\tfor ;\n\tWed, 17 Dec 2025 11:30:39 +0100 (CET)","by mx.zohomail.com with SMTPS id 176596743408147.42195420254427;\n\tWed, 17 Dec 2025 02:30:34 -0800 (PST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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