内存高于4GB时摄像头无法正常工作。当内存从4GB升级到8GB后，打开摄像头APP，终端输出如下

[  100.488782] rga_mm: RGA_MMU unsupported Memory larger than 4G!
[  100.488814] rga_mm: scheduler core[4] unsupported mm_flag[0x0]!
[  100.488821] rga_mm: rga_mm_map_buffer map dma_buf error!
[  100.488826] rga_mm: job buffer map failed!
[  100.488831] rga_mm: dst channel map job buffer failed!
[  100.488834] rga_mm: failed to map buffer
[  100.488842] rga_job: rga_job_commit: failed to map job info
[  100.488896] rga_job: request[1] task[0] job_commit failed.
[  100.488909] rga_job: rga request commit failed!
[  100.488915] rga: request[1] submit failed!

解决方案: 根据文件 ddr_than-4G.patch 修改源码后重新编译。

upgrade_tool 是Linux系统下升级固件的工具。烧录需要超级用户权限。
1. 首先下载并解压 upgrade_tool
2. 将固件和工具放在同一个目录下。
3. 用USB OTG连接电脑和开发板, 长按recovery按键并上电，数秒后松开按键。
4. 使用命令烧录固件。
Basic Commands

  //List devices
  upgrade_tool ld   

  //Download boot
  upgrade_tool db rkxxloader.bin

  //Flash the partition table
  upgrade_tool di -p parameter.txt

  //Flash single partition image
  upgrade_tool di -k kernel.img

  //Falsh multiple partition images
  upgrade_tool di -u uboot.img -b boot.img

  //Flash the partition image with no defined abbreviation, you need to specify the partition name. 
  //Take the vendor partition as an example
  upgrade_tool di -vendor vendor.img

  //When ab partition are used, it also needs to be handled in undefined cases. 
  //Take boot_a and boot_b as example
  upgrade_tool di -boot_a boot.img -boot_b boot.img

  //Flash loader and reset
  upgrade_tool ul rkxxloader.bin  

  //Upgrade firmware and reset
  upgrade_tool uf update.img  

  //Erase device
  upgrade_tool ef rkxxloader.bin