[RFC] drm/amd/display: add SI support to AMD DC

[Deucher, Alexander]

There are two sets of power management code in amdgpu, the older dpm code which was ported from radeon, and the newer powerplay code which was rewritten to align closer with the power management code for other OSes and the hw teams.  The "powerplay" code has more features than the older dpm code, but at a fundamental level, they are pretty much the same.  Both use the same SMU interfaces to support dynamic clock switching.  SI is a bit tricky because it uses and older version of the SMU and an older power management design so it doesn't really match cleanly with the current APIs in the "powerplay" code.


Alex


________________________________
From: sylvain.bertrand at gmail.com <sylvain.bertrand at gmail.com>
Sent: Monday, October 15, 2018 8:45 AM
To: Mauro Rossi
Cc: amd-gfx at lists.freedesktop.org; Wentland, Harry; Deucher, Alexander; Mike Lothian
Subject: Re: [RFC] drm/amd/display: add SI support to AMD DC

On Mon, Oct 15, 2018 at 07:28:57AM +0200, Mauro Rossi wrote:
> dpm for SI is available, while powerplay for SI is not, but
> display/amdgpu_dm uses some powerplay calls, where get_static_clock
> functions not available and the *ERROR* DM_PPLIB is due to missing handling
> in powerplay

I though powerplay was just more power states for the dpm state machines to
play with. I recall parsing ATOMBIOS pplay tables for records of (voltages/clocks
frequencies).

Maybe the future is to trust the OS kernel and perform all "low speed" 3D asic
functions there and keep only high speed 3D operations in the asic.

--
Sylvain
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