【本文正在参加2023年第一期优质创作者激励计划】

前言

本次采用的开发板为扬帆“竞”开发板，扬帆“竞”采用瑞芯微RK3568（Cortex-A55）四核64位超强CPU，搭载OpenHarmony最新操作系统，主频最高达2.0GHz。采用 Mali-G52 GPU，支持4K、H.265/H.264视频解码。
OpenHarmony最新版本的L2标准版图形子系统相比之前版本有着非常大的改动，使用了全新设计的框架，并使用Render Service替换了原来的Weston。图形栈整体上分为三层，从上到下依次为接口层、框架层和引擎层。设计上更加清晰，可以更加的灵活的适配不同的底层图形库和不同的显示硬件，最大限度的发挥硬件性能而不用影响到整体图形栈。

框架层的整体功能如下表，框架层的核心就是Render Service渲染服务。

新的Render Service图形框架默认提供了对OpenGL的支持，并使用API HOOK技术，实现了OpenGL接口和实现的分离，大幅度降低了OpenGL库的适配难度。
扬帆“竞”开发板默认使用的是闭源的libmali-bifrost-g52-g2p0-ohos库，也可以使用开源的Mesa 3D库，实现对OpenGL的支持，在高级图形应用的开发和调试方面非常方便。

使用Mesa库

编译Mesa库

OpenHarmony已经在三方库中集成Mesa库。下载OpenHarmony全量代码，Mesa库在third_party/mesa3d。
进入third_party/mesa3d/目录，OpenHarmony已经提供了编译脚本。其中ohos/build_ohos.py就是针对新图形框架的编译脚本，参考README_zh.md文档，先进行一次全量编译，然后执行。

#python ohos/build_ohos.py </path/to/openharmony> yangfan-j </path/to/openharmony>/third_party/mesa3d

命令编译出mesa库。

生成Mesa组件

1.在device/soc/rockchip/rk3568/hardware/gpu/目录下新建lib-mesa目录，用于存放Mesa 3D库文件。

#mkdir …/device/soc/rockchip/rk3568/hardware/gpu/lib-mesa

2.将编译生成的Mesa 3D库文件拷贝到lib-mesa目录：

#cp build-ohos/install/lib/libgbm.so.1.0.0 ../device/soc/rockchip/rk3568/hardware/gpu/lib-mesa/
#cp build-ohos/install/lib/libglapi.so.0.0.0 ../device/soc/rockchip/rk3568/hardware/gpu/lib-mesa/
#cp build-ohos/src/egl/libEGL.so.1.0.0 ../device/soc/rockchip/rk3568/hardware/gpu/lib-mesa/
#cp build-ohos/install/lib/libGLESv1_CM.so.1.1.0 ../device/soc/rockchip/rk3568/hardware/gpu/lib-mesa/
#cp build-ohos/install/lib/libGLESv2.so.2.0.0 ../device/soc/rockchip/rk3568/hardware/gpu/lib-mesa/
#cp build-ohos/src/gallium/targets/dri/libgallium_dri.so ../ device/soc/rockchip/rk3568/hardware/gpu/lib-mesa/
#cp build-ohos/install/lib/dri/panfrost_dri.so ../device/soc/rockchip/rk3568/hardware/gpu/lib-mesa/

3.修改device/soc/rockchip/rk3568/hardware/gpu/BUILD.gn

index 7d269ac..690a69d 100644
--- a/rk3568/hardware/gpu/BUILD.gn
+++ b/rk3568/hardware/gpu/BUILD.gn
@@ -47,3 +47,108 @@ ohos_prebuilt_shared_library("mali-bifrost-g52-g2p0-ohos") {
     "libmali.so.1",
   ]
 }
+
+ohos_prebuilt_shared_library("mesa_gbm") {
+  source = "lib-mesa/libgbm.so.1.0.0"
+  install_enable = true
+  install_images = [ chipset_base_dir ]
+  relative_install_dir = "chipsetsdk"
+  subsystem_name = "rockchip_products"
+  part_name = "rockchip_products"
+  symlink_target_name = [
+    "libgbm.so.1",
+    "libgbm.so",
+  ]
+}
+
+ohos_prebuilt_shared_library("mesa_egl") {
+  source = "lib-mesa/libEGL.so.1.0.0"
+  install_enable = true
+  install_images = [ chipset_base_dir ]
+  relative_install_dir = "chipsetsdk"
+  subsystem_name = "rockchip_products"
+  part_name = "rockchip_products"
+  symlink_target_name = [
+    "libEGL.so.1",
+    "libEGL.so",
+    "libGLESv1.so",
+    "libEGL_impl.so",
+  ]
+}
+
+ohos_prebuilt_shared_library("mesa_glapi") {
+  source = "lib-mesa/libglapi.so.0.0.0"
+  install_enable = true
+  install_images = [ chipset_base_dir ]
+  relative_install_dir = "chipsetsdk"
+  subsystem_name = "rockchip_products"
+  part_name = "rockchip_products"
+  symlink_target_name = [
+    "libglapi.so.0",
+    "libglapi.so",
+  ]
+}
+
+ohos_prebuilt_shared_library("mesa_glesv1") {
+  source = "lib-mesa/libGLESv1_CM.so.1.1.0"
+  install_enable = true
+  install_images = [ chipset_base_dir ]
+  relative_install_dir = "chipsetsdk"
+  subsystem_name = "rockchip_products"
+  part_name = "rockchip_products"
+  symlink_target_name = [
+    "libGLESv1_CM.so.1",
+    "libGLESv1_CM.so",
+    "libGLESv1_impl.so",
+  ]
+}
+
+ohos_prebuilt_shared_library("mesa_glesv2") {
+  source = "lib-mesa/libGLESv2.so.2.0.0"
+  install_enable = true
+  install_images = [ chipset_base_dir ]
+  relative_install_dir = "chipsetsdk"
+  subsystem_name = "rockchip_products"
+  part_name = "rockchip_products"
+  symlink_target_name = [
+    "libGLESv2.so.2",
+    "libGLESv2.so",
+    "libGLESv2_impl.so",
+    "libGLESv3_impl.so",
+  ]
+}
+
+ohos_prebuilt_shared_library("libgallium_dri") {
+  source = "lib-mesa/libgallium_dri.so"
+  install_enable = true
+  install_images = [ chipset_base_dir ]
+  relative_install_dir = "chipsetsdk"
+  subsystem_name = "rockchip_products"
+  part_name = "rockchip_products"
+  symlink_target_name = [ "libgallium_dri.so" ]
+}
+
+ohos_prebuilt_shared_library("panfrost_dri") {
+  source = "lib-mesa/panfrost_dri.so"
+  install_enable = true
+  install_images = [ "system" ]
+  subsystem_name = "rockchip_products"
+  part_name = "rockchip_products"
+  symlink_target_name = [
+    "rockchip_dri.so",
+    "libmali.so.0",
+    "libmali.so.1",
+  ]
+}
+
+group("mesa-gpu") {
+  public_deps = [
+    ":mesa_egl",
+    ":mesa_gbm",
+    ":mesa_glapi",
+    ":mesa_glesv1",
+    ":mesa_glesv2",
+    ":libgallium_dri",
+    ":panfrost_dri",
+  ]
+}

4.修改device/soc/rockchip/rk3568/hardware/BUILD.gn，使用Mesa 3D库

index 479847d..e778fb0 100644
--- a/rk3568/hardware/BUILD.gn
+++ b/rk3568/hardware/BUILD.gn
@@ -15,7 +15,8 @@ import("//build/ohos.gni")
 
 group("hardware_group") {
   deps = [
-    "//device/soc/rockchip/rk3568/hardware/gpu:mali-bifrost-g52-g2p0-ohos",
+    #"//device/soc/rockchip/rk3568/hardware/gpu:mali-bifrost-g52-g2p0-ohos",
+    "//device/soc/rockchip/rk3568/hardware/gpu:mesa-gpu",
     "//device/soc/rockchip/rk3568/hardware/isp:isp",
     "//device/soc/rockchip/rk3568/hardware/mpp:mpp",
     "//device/soc/rockchip/rk3568/hardware/wifi:ap6xxx",

修改内核的配置文件

修改内核配置文件，启用panforst驱动。

index 9a9501c..52b3232 100644
--- a/linux-5.10/arch/arm64/configs/yangfan-j_standard_defconfig
+++ b/linux-5.10/arch/arm64/configs/yangfan-j_standard_defconfig
@@ -3622,7 +3622,7 @@ CONFIG_DVB_SP2=m
 #
 # CONFIG_VGA_ARB is not set
 CONFIG_DRM=y
-CONFIG_DRM_IGNORE_IOTCL_PERMIT=y
+# CONFIG_DRM_IGNORE_IOTCL_PERMIT is not set
 CONFIG_DRM_MIPI_DSI=y
 # CONFIG_DRM_DP_AUX_CHARDEV is not set
 # CONFIG_DRM_DEBUG_MM is not set
@@ -3636,6 +3636,8 @@ CONFIG_DRM_FBDEV_OVERALLOC=100
 CONFIG_DRM_LOAD_EDID_FIRMWARE=y
 # CONFIG_DRM_DP_CEC is not set
 CONFIG_DRM_GEM_CMA_HELPER=y
+CONFIG_DRM_GEM_SHMEM_HELPER=y
+CONFIG_DRM_SCHED=y
 
 #
 # I2C encoder or helper chips
@@ -3793,7 +3795,7 @@ CONFIG_DRM_DW_MIPI_DSI=y
 # CONFIG_TINYDRM_ST7735R is not set
 # CONFIG_DRM_PL111 is not set
 # CONFIG_DRM_LIMA is not set
-# CONFIG_DRM_PANFROST is not set
+CONFIG_DRM_PANFROST=y
 # CONFIG_DRM_TIDSS is not set
 # CONFIG_DRM_LEGACY is not set
 CONFIG_DRM_PANEL_ORIENTATION_QUIRKS=y

修改扬帆“竞”内核补丁

内核补丁需要在Linux系统上使用vim编辑器修改，Windows编辑器修改可能导致编译错误。

index 41a7df5..1a5e5a3 100644
--- a/linux-5.10/yangfan-j_patch/kernel.patch
+++ b/linux-5.10/yangfan-j_patch/kernel.patch
@@ -100948,36 +100948,36 @@ index 000000000..372617fee
 +	};
 +
 +	gpu: gpu@fde60000 {
-+		compatible = "arm,mali-bifrost";
-+		reg = <0x0 0xfde60000 0x0 0x4000>;
++		compatible = "rockchip, rk3568-mali","arm,mali-bifrost";
++		reg = <0x0 0xfde60000 0x0 0x20000>;
 +
-+		interrupts = <GIC_SPI 39 IRQ_TYPE_LEVEL_HIGH>,
++		interrupts = <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>,
 +			     <GIC_SPI 41 IRQ_TYPE_LEVEL_HIGH>,
-+			     <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>;
-+		interrupt-names = "GPU", "MMU", "JOB";
++			     <GIC_SPI 39 IRQ_TYPE_LEVEL_HIGH>;
++		interrupt-names = "job", "mmu", "gpu";
 +
-+		upthreshold = <40>;
-+		downdifferential = <10>;
++		/* upthreshold = <40>; */
++		/* downdifferential = <10>; */
 +
 +		clocks = <&scmi_clk 1>, <&cru CLK_GPU>;
-+		clock-names = "clk_mali", "clk_gpu";
++		clock-names = "core", "bus";
 +		power-domains = <&power RK3568_PD_GPU>;
 +		#cooling-cells = <2>;
 +		operating-points-v2 = <&gpu_opp_table>;
 +
 +		status = "disabled";
-+		gpu_power_model: power-model {
-+			compatible = "simple-power-model";
-+			leakage-range= <5 15>;
-+			ls = <(-24002) 22823 0>;
-+			static-coefficient = <100000>;
-+			dynamic-coefficient = <953>;
-+			ts = <(-108890) 63610 (-1355) 20>;
-+			thermal-zone = "gpu-thermal";
-+		};
-+	};
-+
-+	gpu_opp_table: opp-table2 {
++		/* gpu_power_model: power-model { */
++		/*	compatible = "simple-power-model"; */
++		/*	leakage-range= <5 15>; */
++		/*	ls = <(-24002) 22823 0>; */
++		/*	static-coefficient = <100000>; */
++		/*	dynamic-coefficient = <953>; */
++		/*	ts = <(-108890) 63610 (-1355) 20>; */
++		/*	thermal-zone = "gpu-thermal"; */
++		/* }; */
++	};
++
++	gpu_opp_table: gpu-opp-table {
 +		compatible = "operating-points-v2";
 +
 +		mbist-vmin = <825000 900000 950000>;

测试和验证

1.查看GPU中断，panforst驱动已经正常工作。桌面显示和操作正常

2.游戏效果

测试表明，扬帆“竞”开发板的图形界面使用正常且流畅，基础应用都可以正常运行，体验与使用libmali-g52库基本一致。