| Bug ID | 108573 |
|---|---|
| Summary | Cannot set pstate values with under-voltage values for Vega M |
| Product | DRI |
| Version | unspecified |
| Hardware | x86-64 (AMD64) |
| OS | Linux (All) |
| Status | NEW |
| Severity | normal |
| Priority | medium |
| Component | DRM/AMDgpu |
| Assignee | dri-devel@lists.freedesktop.org |
| Reporter | rstrube@gmail.com |
There are some folks on the Windows side of the fence that have had great success under-volting their Vega M chips to improve thermals (and because TDP is shared between the CPU and GPU on Kaby Lake G, also their overall performance). Following information from the amdgpu kernel documentation I applied the following kernel boot parameters: amdgpu.runpm=0 amdgpu.ppfeaturemask=0xffffffff Note: I needed the runpm=0 so that the Vega M is active at all times, otherwise it powers down and I'm unable to make any changes to the pstates using the sysfs API. Then doing the following I was able to see the current pstates: cat /sys/bus/pci/drivers/amdgpu/0000:01:00.0/pp_od_clk_voltage OD_SCLK: 0: 225MHz 750mV 1: 400MHz 750mV 2: 535MHz 750mV 3: 715MHz 750mV 4: 850MHz 750mV 5: 960MHz 750mV 6: 985MHz 750mV 7: 1011MHz 750mV OD_MCLK: 0: 300MHz 750mV 1: 500MHz 750mV 2: 700MHz 750mV OD_RANGE: SCLK: 225MHz 1011MHz MCLK: 300MHz 700MHz VDDC: 750mV 750mV Then this to support updating the pstates: echo "manual" > /sys/bus/pci/drivers/amdgpu/0000:01:00.0/power_dpm_force_performance_level Then I could push in new pstates values, provided the voltage was *exactly* 750mV. I could set a higher clock speed for a pstate, but I was unable to make any changes to the voltage. echo "s 0 226 750" > /sys/bus/pci/drivers/amdgpu/0000:01:00.0/pp_od_clk_voltage works and increases the MHz from 225 -> 226 for pstate 0, but echo "s 0 226 749" > /sys/bus/pci/drivers/amdgpu/0000:01:00.0/pp_od_clk_voltage -bash: echo: write error: Invalid argument Checking dmesg I see that the voltage range is constrained between 750 and 750. [ 4362.487021] amdgpu: [powerplay] OD voltage is out of range [750 - 750] mV Would it be possible to add support for under-volting Vega M using the sysfs API? I also noticed that it's not possible to set any pstate higher than 1011 MHz, perhaps that's a harder sell, but it might also be nice to be able to overclock the Vega M a little! P.S. I tried finding these values in the kernel source code, but I was extremely confused about the way they are defined. I figured worse case scenario I could manually modify these limits and recompile the kernel. Thanks! Rob
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