Hi, 
I have a Dell E6540 with HD 8790M (MARS XTX)
I also have the `radeon.si_support=0 amdgpu.si_support=1` kernel flags set to enable experimental amdgpu support.

I run games such as Insurgency, Tomb Raider (2013), Talos Principle, and Half-Life 2 Episode 1 from it with the `DRI_PRIME=1` env variable.

On all of these games, they seem to perform underwhelmingly (under 30fps for most games), until I suspend the computer and wake it from suspension. (This even works while in game).

Here are some things I've noticed:
1. setting the `amdgpu.dpm=0` kernel flag makes it so that suspending the computer and waking it up DOES NOT double/triple the gaming graphics performance like it usually does.
2. setting `/sys/class/drm/card1/device/power_dpm_force_performance_level` or `/sys/class/drm/card1/device/power_dpm_state` before having suspended the computer does not noticeably impact performance.
3. If I reboot the computer after having suspended it, instead of shutting down or hibernating, it seems to at least sometime hold on to its gaming graphics performance so that I don't need to suspend the computer once more while playing a game.
4. This suspend-wakeup performance improvement does not seem reproducible on RadeonSI (`radeon.si_support=1`), although I can't tell if it's lower performance or higher, since it'll perform well in Half-Life 2, but closer to the reduced (pre-suspend) performance state in many other games.
5. Wayland or X11 makes no difference.
6. Games using the Intel IGP are not affected by suspend + wake.

In the below Log's dmesg, I suspend and wake up the computer at ~1588

LOG:
[travis@Claes ~]$ dmesg | grep -E -i "dpm|amdgpu|radeon"
[    0.000000] Command line: BOOT_IMAGE=(hd0,msdos2)/vmlinuz-5.4.12-200.fc31.x86_64 root=/dev/mapper/altarus-root ro resume=/dev/mapper/altarus-swap rd.lvm.lv=altarus/root rd.lvm.lv=altarus/swap rhgb quiet radeon.si_support=0 amdgpu.si_support=1 zswap.enabled=1 zswap.compressor=lz4 zswap.zpool=z3fold amdgpu.dpm=1 amdgpu.dc=1
[    0.129882] Kernel command line: BOOT_IMAGE=(hd0,msdos2)/vmlinuz-5.4.12-200.fc31.x86_64 root=/dev/mapper/altarus-root ro resume=/dev/mapper/altarus-swap rd.lvm.lv=altarus/root rd.lvm.lv=altarus/swap rhgb quiet radeon.si_support=0 amdgpu.si_support=1 zswap.enabled=1 zswap.compressor=lz4 zswap.zpool=z3fold amdgpu.dpm=1 amdgpu.dc=1
[    3.018497] [drm] radeon kernel modesetting enabled.
[    3.018785] radeon 0000:01:00.0: SI support disabled by module param
[    3.271878] [drm] amdgpu kernel modesetting enabled.
[    3.272148] amdgpu 0000:01:00.0: remove_conflicting_pci_framebuffers: bar 0: 0xe0000000 -> 0xefffffff
[    3.272149] amdgpu 0000:01:00.0: remove_conflicting_pci_framebuffers: bar 2: 0xf7c00000 -> 0xf7c3ffff
[    3.272158] amdgpu 0000:01:00.0: enabling device (0000 -> 0003)
[    3.272841] [drm] add ip block number 5 <si_dpm>
[    3.272843] amdgpu 0000:01:00.0: kfd not supported on this ASIC
[    3.306053] amdgpu 0000:01:00.0: VRAM: 2048M 0x000000F400000000 - 0x000000F47FFFFFFF (2048M used)
[    3.306054] amdgpu 0000:01:00.0: GART: 1024M 0x000000FF00000000 - 0x000000FF3FFFFFFF
[    3.306399] [drm] amdgpu: 2048M of VRAM memory ready
[    3.306401] [drm] amdgpu: 3072M of GTT memory ready.
[    3.306899] amdgpu 0000:01:00.0: PCIE GART of 1024M enabled (table at 0x000000F400000000).
[    3.307310] [drm] amdgpu: dpm initialized
[    3.307352] [drm] AMDGPU Display Connectors
[    3.878634] [drm] Initialized amdgpu 3.35.0 20150101 for 0000:01:00.0 on minor 1
[   12.958605] amdgpu 0000:01:00.0: PCIE GART of 1024M enabled (table at 0x000000F400000000).
[   27.123524] amdgpu 0000:01:00.0: PCIE GART of 1024M enabled (table at 0x000000F400000000).
[ 1588.479472] amdgpu 0000:01:00.0: PCIE GART of 1024M enabled (table at 0x000000F400000000).
[ 1590.890634] amdgpu 0000:01:00.0: PCIE GART of 1024M enabled (table at 0x000000F400000000).
[ 1676.994027] amdgpu 0000:01:00.0: PCIE GART of 1024M enabled (table at 0x000000F400000000).

[travis@Claes ~]$ DRI_PRIME=1 glxinfo -B
name of display: :1
display: :1  screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: X.Org (0x1002)
    Device: AMD Radeon HD 8790M (OLAND, DRM 3.35.0, 5.4.12-200.fc31.x86_64, LLVM 9.0.0) (0x6606)
    Version: 19.2.8
    Accelerated: yes
    Video memory: 2048MB
    Unified memory: no
    Preferred profile: core (0x1)
    Max core profile version: 4.5
    Max compat profile version: 4.5
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.2
Memory info (GL_ATI_meminfo):
    VBO free memory - total: 2039 MB, largest block: 2039 MB
    VBO free aux. memory - total: 3055 MB, largest block: 3055 MB
    Texture free memory - total: 2039 MB, largest block: 2039 MB
    Texture free aux. memory - total: 3055 MB, largest block: 3055 MB
    Renderbuffer free memory - total: 2039 MB, largest block: 2039 MB
    Renderbuffer free aux. memory - total: 3055 MB, largest block: 3055 MB
Memory info (GL_NVX_gpu_memory_info):
    Dedicated video memory: 2048 MB
    Total available memory: 5120 MB
    Currently available dedicated video memory: 2039 MB
OpenGL vendor string: X.Org
OpenGL renderer string: AMD Radeon HD 8790M (OLAND, DRM 3.35.0, 5.4.12-200.fc31.x86_64, LLVM 9.0.0)
OpenGL core profile version string: 4.5 (Core Profile) Mesa 19.2.8
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 4.5 (Compatibility Profile) Mesa 19.2.8
OpenGL shading language version string: 4.50
OpenGL context flags: (none)
OpenGL profile mask: compatibility profile

OpenGL ES profile version string: OpenGL ES 3.2 Mesa 19.2.8
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20

[travis@Claes ~]$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller (rev 06)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Mars XTX [Radeon HD 8790M]