Hi xiaojun,
Please refer to attached Linux Manual Chapter 23-25 for description of thermal driver. Also please check AN4579 "Thermal Management Guidelines for the i.MX 6Dual/6Quad" for more details. http://www.nxp.com/doc/AN4579
But when temperature reach passive point , I can see the log shows "System is too hot. GPU3D will work at 1/64 clock." and check GPU clock by "cat /sys/kernel/debug/clk/clk_summary | grep gpu" , the GPU3D clock still 594MHz . imx6qsabresd:~# cat /sys/kernel/debug/clk/clk_summary | grep gpu gpu2d_core_sel 0 0 480000000 0 gpu2d_core_podf 0 0 480000000 0 gpu2d_core 0 0 480000000 0 gpu3d_axi 0 0 270000000 0 gpu2d_axi 0 0 270000000 0 gpu3d_core_sel 0 0 528000000 0 gpu3d_core_podf 0 0 528000000 0 gpu3d_core 0 0 528000000 0 gpu3d_shader_sel 0 0 594000000 0 gpu3d_shader 0 0 594000000 0
