[{"id":37193,"web_url":"https://patchwork.libcamera.org/comment/37193/","msgid":"<85a4zz37ce.fsf@mzamazal-thinkpadp1gen7.tpbc.csb>","date":"2025-12-03T15:36:49","subject":"Re: [PATCH v6 01/24] libcamera: software_isp: gbm: Add a GBM helper\n\tclass for GPU surface access","submitter":{"id":177,"url":"https://patchwork.libcamera.org/api/people/177/","name":"Milan Zamazal","email":"mzamazal@redhat.com"},"content":"https://lists.libcamera.org/pipermail/libcamera-devel/2025-June/050901.html\nstill not addressed.\n\nBryan O'Donoghue writes:\n\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> 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 | 11 +++\n> 4 files changed, 181 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..6852def58\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> + * gbm.h - 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 *gbm_device_;\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..7d53cd43e\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> + * egl.cpp - 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::gbm_device_\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> +\tgbm_device_ = NULL;\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 (gbm_device_)\n> +\t\tgbm_device_destroy(gbm_device_);\n> +}\n> +\n> +/**\n> + * \\brief Create and initialize a GBM device\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\"; //TODO: get from an env or config setting\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> +\tgbm_device_ = gbm_create_device(fd_);\n> +\tif (!gbm_device_) {\n> +\t\tLOG(GBM, Error) << \"gbm_crate_device fail\";\n> +\t\tgoto fail;\n> +\t}\n> +\n> +\tformat_ = libcamera::formats::ARGB8888;\n> +\n> +\treturn 0;\n> +fail:\n> +\tclose(fd_);\n> +\treturn -errno;\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 gbm_device_;\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 90d434a5a..4eaa42062 100644\n> --- a/src/libcamera/meson.build\n> +++ b/src/libcamera/meson.build\n> @@ -70,6 +70,16 @@ 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> + config_h.set('HAVE_GBM', 1)\n> + libcamera_internal_sources += files([\n> + 'gbm.cpp',\n> + ])\n> +endif\n> +\n> subdir('base')\n> subdir('converter')\n> subdir('ipa')\n> @@ -178,6 +188,7 @@ 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 E933FBD80A\n\tfor ;\n\tWed, 3 Dec 2025 15:36:57 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id E006360F5F;\n\tWed, 3 Dec 2025 16:36:56 +0100 (CET)","from us-smtp-delivery-124.mimecast.com\n\t(us-smtp-delivery-124.mimecast.com [170.10.129.124])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 80D07609D8\n\tfor ;\n\tWed, 3 Dec 2025 16:36:55 +0100 (CET)","from mail-wm1-f70.google.com (mail-wm1-f70.google.com\n\t[209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS\n\t(version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id\n\tus-mta-307-mWDsg7IsPqKHwS5-fEMPTg-1; Wed, 03 Dec 2025 10:36:53 -0500","by mail-wm1-f70.google.com with SMTP id\n\t5b1f17b1804b1-477a0ddd1d4so38444455e9.0\n\tfor ;\n\tWed, 03 Dec 2025 07:36:53 -0800 (PST)","from mzamazal-thinkpadp1gen7.tpbc.csb\n\t(ip-77-48-47-2.net.vodafone.cz. 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