[Intel-gfx] [PATCH] drm/i915: Disable DMC powersaving during GT operations

[Tahvanainen, Jari]

Hello,

+Ricardo related to testing done by GFX QA.

Br, Jari

-----Original Message-----
From: Joonas Lahtinen [mailto:joonas.lahtinen at linux.intel.com] 
Sent: Monday, September 18, 2017 4:41 PM
To: Chris Wilson <chris at chris-wilson.co.uk>; intel-gfx at lists.freedesktop.org
Cc: Ursulin, Tvrtko <tvrtko.ursulin at intel.com>; Deak, Imre <imre.deak at intel.com>; Tahvanainen, Jari <jari.tahvanainen at intel.com>; Kaajas, Samu <samu.kaajas at intel.com>
Subject: Re: [PATCH] drm/i915: Disable DMC powersaving during GT operations

+ Jari & Samu

On Tue, 2017-09-12 at 13:48 +0100, Chris Wilson wrote:
> Quoting Chris Wilson (2017-09-12 13:37:32)
> > diff --git a/drivers/gpu/drm/i915/i915_gem_request.c 
> > b/drivers/gpu/drm/i915/i915_gem_request.c
> > index 813a3b546d6e..3c8ebdb5b0b4 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_request.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_request.c
> > @@ -254,6 +254,9 @@ static void mark_busy(struct drm_i915_private *i915)
> >         intel_runtime_pm_get_noresume(i915);
> >         i915->gt.awake = true;
> >  
> 
> /*
>  * The DMC doesn't behave well when it is active (i.e the system is
>  * idle). It continually tries to toggle DC_STATE_EN causing a
>  * severe slow down of the rest of the system (severe enough to 
> trigger
>  * watchdogs and reboot the machine under CI testing).
>  *
>  * Known affected firmware:
>  * - skl_dmc_ver1_26.bin
>  * - bxt_dmc_ver1_07.bin
>  */

Has this patch been tested more widely, does it have negative performance effects?

Regards, Joonas

> > +       if (i915->csr.dmc_payload)
> > +               intel_display_power_get(i915, POWER_DOMAIN_MODESET);
> > +
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation