From: bugzilla-daemon@freedesktop.org
To: dri-devel@lists.freedesktop.org
Subject: [Bug 108573] Cannot set pstate values with under-voltage values for Vega M
Date: Fri, 26 Oct 2018 23:54:58 +0000 [thread overview]
Message-ID: <bug-108573-502@http.bugs.freedesktop.org/> (raw)
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https://bugs.freedesktop.org/show_bug.cgi?id=108573
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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next reply other threads:[~2018-10-26 23:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-26 23:54 bugzilla-daemon [this message]
2018-10-29 15:07 ` [Bug 108573] Cannot set pstate values with under-voltage values for Vega M bugzilla-daemon
2019-11-19 9:00 ` bugzilla-daemon
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