ATI Kernel Power Management Moves A Bit More

On Sunday we reported that ATI in-kernel power management was moving along after AMD's Alex Deucher spent some time in recent days building upon Rafał Miłecki's initial power management support. Alex's patches added GUI idle IRQ support, support for changing the GPU clocks when the engine is idle, support for turning down the number of active SIMDS when running in a lower power stage for the ATI R600 ASICs and later, and new ASIC specific callback functions. This morning though he's taken the support a bit further.

With Alex's brand new patch, hwmon drivers can now be loaded for the I2C thermal chips found on many ATI graphics cards. In other words, we finally have thermal monitoring and fan speed support for the open-source ATI stack! Though it's not finished yet as the hwmon readings aren't exposed to the Radeon DRM yet so it isn't yet able to leverage this data internally. This though will come. Additionally, Alex is still battling support for voltage adjustments when switching power states, fine tuning the re-clocking algorithm, and letting the Radeon DRM read the AC/battery power state.

This newest power management code can be found in the drm-radeon-testing branch and will hopefully be ready to go in the mainline kernel by the Linux 2.6.35 kernel this summer. Details on the newest ATI power management work can be found in Alex's blog post.