内核代码下载
# 需要在apt的sources.list中加入 deb-src 行，告诉apt源码仓库的具体位置等信息
sudo apt update # 需要系统权限，更新仓库数据库
apt source linux # 不需要系统权限，用户目录下运行，命令下载源代码包并解压
龙芯桥片集成显卡的一些信息收集
- 截止目前，龙芯公开发售的桥片有两个，7A1000 和 7A2000
- 桥片内置的集成显卡内核驱动分成两部分，一部分是显示控制，一部分是GPU控制
- 显示控制的驱动源码目录： src/drivers/gpu/drm/loongson 和 src/drivers/gpu/drm/lsdc
- 显示控制驱动支持 7A1000&2000，主要功能是KMS（内核态的显示模式控制）和 TTM（内核态的显存管理）
- 这个驱动支持桥片外置显存的管理，和GPU配合，支持3D加速功能
- 图形处理单元GPU驱动，提供3D硬件加速功能，
- 7A1000的GPU是atnaviv的GC1000 ip
- 驱动源码目录： src/drivers/gpu/drm/etnaviv
- 7A2000的GPU是龙芯LG100系列图形处理核心
- 内核驱动源码目录： src/drivers/gpu/gsgpu
- 这两个图形处理核心的dri驱动可以在loongnix仓库中找到 apt source mesa
- 可以使用 lsmod 查看这两个驱动的加载情况，也可以通过访问 /dev/dri 查看一些细节
代码漫游
内核配置选项
# 7A1000 GPU内核驱动
CONFIG_DRM_ETNAVIV=m
CONFIG_DRM_ETNAVIV_PCI_DRIVER=y
CONFIG_DRM_ETNAVIV_THERMAL=y
# 桥片显示控制内核驱动
CONFIG_DRM_LOONGSON_VGA=m
# amd显卡的内核驱动
CONFIG_DRM_RADEON=m
CONFIG_DRM_RADEON_USERPTR=y
CONFIG_DRM_AMDGPU=m
CONFIG_DRM_AMDGPU_SI=y
CONFIG_DRM_AMDGPU_CIK=y
CONFIG_DRM_AMDGPU_USERPTR=y
src/drivers/gpu/drm/loongson
config DRM_LOONGSON_VGA
tristate "DRM support for loongson chipset and soc"
depends on DRM && PCI
select FB_SYS_FILLRECT
select FB_SYS_COPYAREA
select FB_SYS_IMAGEBLIT
select DRM_KMS_HELPER
select DRM_KMS_FB_HELPER
select DRM_TTM
select REGMAP_I2C
select VIDEOMODE_HELPERS
default n
help
DRM display driver for loongson vga control.
config DRM_LOONGSON_VGA_PLATFORM
bool "use platfrom device"
depends on DRM_LOONGSON_VGA && CPU_LOONGSON2K
help
This option selects CONFIG_MMU_NOTIFIER if it isn't already
selected to enabled full userptr support.
src/drivers/gpu/drm/lsdc
config DRM_LSDC
tristate "Kernel modesetting driver for loongson display controller"
depends on DRM
depends on MACH_LOONGSON64 || LOONGARCH || COMPILE_TEST
select OF
select CMA if HAVE_DMA_CONTIGUOUS
select DMA_CMA if HAVE_DMA_CONTIGUOUS
select DRM_KMS_HELPER
select DRM_KMS_FB_HELPER
select DRM_GEM_CMA_HELPER
select DRM_KMS_CMA_HELPER
select VIDEOMODE_HELPERS
select BACKLIGHT_PWM
select REGULATOR
select REGULATOR_FIXED_VOLTAGE
select DRM_PANEL_SIMPLE
select DRM_DUMB_VGA_DAC
select DRM_SII902X
select DRM_LT8618
select DRM_TI_TFP410
select I2C_GPIO
select I2C_LS2X
default m
help
This is a KMS driver for the display controller in the LS7A1000
bridge chip and LS2K1000 SoC.
Note that this driver is different from the loongson KMS
driver (loongson.ko), the loongson KMS driver using TTM
memory manager and its framebuffer is allocated from VRAM.
This driver is based-on CMA and DMA_CMA, its framebuffer
is located from system memory. By default, this driver is
not enabled on LS7A1000 + LS3A3000/LS3A4000 platform.
Pass the following parameter to the kernel commnad line
if you would like to have a try.
loongson.enable=0 lsdc.modeset=1
If "M" is selected, the module will be called lsdc.
If in doubt, say "Y".
config DRM_LSDC_PCI_DRIVER
bool "Enable pci device driver support for DC in LS7A1000 Bridge"
depends on DRM_LSDC
depends on PCI
default y
help
Choose this if you want to build CMA-base KMS driver
for the display controller in LS7A1000.
DRM_LSDC_PCI_DRIVER will be defined on when the dc is a pci device
If in doubt, say "Y".
