[Bug 96487] Cannot force power_dpm_force_performance_level to high

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=96487

            Bug ID: 96487
           Summary: Cannot force power_dpm_force_performance_level to high
           Product: DRI
           Version: XOrg git
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Radeon
          Assignee: dri-devel at lists.freedesktop.org
          Reporter: ltjbour at gmail.com

Created attachment 124464
  --> https://bugs.freedesktop.org/attachment.cgi?id=124464&action=edit
Information about the supported gpu states

Linux 4.6.2-1-ARCH #1 SMP PREEMPT Wed Jun 8 08:40:59 CEST 2016 x86_64 GNU/Linux

I thought my problem was perhaps a duplicate of
https://bugs.freedesktop.org/show_bug.cgi?id=70654 but I'm pretty sure that
this isn't the same problem. The problem I'm having is that I can't set the
highest frequency state from my gpu (AMD A8-4500M APU + HD 7640G), in a
consistent and persistent way. And this is regardless of whether uvd is enabled
or not (as I assume this is enabled automatically and I haven't been running
any application that requires it)

In other words I would like to be able to set the dpm level to 'high' so that
it stays in the higher frequency state, but I can't set the
power_dpm_force_performance variable to anything other than 'auto' and 'low'. I
get the following output:


λ echo high | sudo tee
/sys/class/drm/card0/device/power_dpm_force_performance_level
high
tee: /sys/class/drm/card0/device/power_dpm_force_performance_level: Invalid
argument


It turns out that after some testing, I have noticed that it's more stable to
set 'performance' dpm state and force it to 'low', which leaves the GPU
frequency at ~335MHz, than setting it to auto which makes the frequencies jump
between modes [335/490/655]MHz depending on the load. I would obviously like to
be able to set a single mode and have a constant frequency. If I can set 655MHz
permanently that would be ideal.

I've already tried using 'dynpm' and 'profile' modes, but they don't work. I
tried a bunch of times, even enabled/disabled some radeon parameters to see if
they were somehow conflicting but I wasn't able to succesfully change states a
single time. It would permanently stay at 200MHz with either of these two
profile modes set. That left me with the single choice of using 'dpm', as it
was the only mode that was able to at least change the states.

I was told in IRC that the reason I couldn't set the 'high' value permanently
was due to a hardware limitation of Trinity chips. I don't see how this can
possibly be true as I can get this same GPU to be consistently at its highest
frequency state in Windows 8. So if anything this is a limitation of the
driver?

I've attached the kernel info about the available states, the list of radeon
parameters and their values in my system, and the output of /proc/cpuinfo. As
of now I don't know what else to add so feel free to ask for any additional
information, I'll make it available as soon as I can.

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