Better Fan Control Support Coming To The Open-Source Radeon Driver
In tackling FreeDesktop.org Bug #73338 that's been open since January, Alex Deucher has been working on improved fan control support for the Radeon HD 7000 graphics processors and newer. The original bug report explained, "I have a brand new MSI AMD Radeon R9 270 2G GAMING. When the computer starts (during POST and grub screen and system boot), its fan is clearly audible - at 40% by my estimate. As soon as I hit a login screen, either in Windows or in Linux with catalyst driver, the fan becomes _very_ silent (at 18% by my estimate). But with radeonsi driver, the slowdown never happens - it's spinning at the original speed of 40% all the time (I guess it would just go up if I were able to utilize the card to its full potential)...My problem with radeonsi is that my computer is quite loud compared to a system with catalyst (Windows or Linux)."
Alex wrote some patches in September to try to take care of the SI/CI fan control but was held up by AMD's internal IP review procedures and they had then been available for testing since October in a Git branch. Alex has now sent out these patches to the DRI-devel list as what could potentially be material for the Linux 3.19 kernel otherwise Linux 3.20.
The patches implement SI SMC fan control and CI SMC fan control. The patch message says, "Enable smc fan control for CI boards. Should reduce the fan noise on systems with a higher default fan profile." However, the code is disabled by default.
There's also other patches part of this series of 11 patches in total. The other patches include changes to apply voltage changes before clock changes, disabling needless clock changes, unused CI thermal DPM support, etc.