Last year Valve contractor Timur Kristóf managed to improve the AMDGPU driver enough for old GCN 1.0 Southern Islands and GCN 1.1 Sea Islands GPUs that with Linux 6.19 AMDGPU is now the default for those GPUs with better performance, RADV Vulkan out-of-the-box, and other benefits. He isn’t done though improving the old GCN 1.0/1.1 era GPU support on this modern AMDGPU kernel driver – a new patch series posted today brings some power management fixes.
Timur Kristóf posted a new patch series today focused on AMDGPU driver power management fixes for the GCN 1.0 graphics processors. This patch series is that very latest work for benefiting these 14 year old graphics processors.
The patches include avoiding some unnecessary work around recalculating power limits, fixing a power management issue for the Radeon 430 GPU, and better handling power2_cap when not being able to read the power limit for a given graphics card,
The Radeon R5 430 power management fix is the most notable of this patch series as it’s important for performance in being able to push the card to its rated clocks:
“On the Radeon 430, powertune is buggy and throttles the GPU, never allowing it to reach its maximum SCLK. Work around this bug by raising the TDP limits we program to the SMC from 24W (specified by the VBIOS on Radeon 430) to 32W.
Disabling powertune entirely is not a viable workaround, becauseit causes the Radeon 520 to heat up above 100 C, which I prefer to avoid.
Additionally, revise the maximum SCLK limit. Considering the above issue, these GPUs never reached a high SCLK on Linux, and the workarounds were added before the GPUs were released, so the workaround likely didn’t target these specifically. Use 780 MHz (the maximum SCLK according to the VBIOS on the Radeon 430). Note that the Radeon 520 VBIOS has a higher maximum SCLK: 905 MHz, but in practice it doesn’t seem to perform better with the higher clock, only heats up more.”
This latest open-source graphics driver code for old AMD GPUs courtesy of Valve is now under review.
