linux-kernel - Re: [PATCH v2] drm/radeon/dpm: Disable sclk switching on Oland when two 4K 60Hz monitors are connected

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Message-ID: <CADnq5_OVQv2K_30uWN7qwUsGVWD7bc7qAs-s_TL-m8NLCDSkOw@mail.gmail.com>
Date:   Tue, 11 May 2021 16:12:49 -0400
From:   Alex Deucher <alexdeucher@...il.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     "Deucher, Alexander" <alexander.deucher@....com>,
        Christian Koenig <christian.koenig@....com>,
        David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        "open list:RADEON and AMDGPU DRM DRIVERS" 
        <amd-gfx@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm/radeon/dpm: Disable sclk switching on Oland when
 two 4K 60Hz monitors are connected

On Mon, May 10, 2021 at 11:33 PM Kai-Heng Feng
<kai.heng.feng@...onical.com> wrote:
>
> On Fri, Apr 30, 2021 at 12:57 PM Kai-Heng Feng
> <kai.heng.feng@...onical.com> wrote:
> >
> > Screen flickers rapidly when two 4K 60Hz monitors are in use. This issue
> > doesn't happen when one monitor is 4K 60Hz (pixelclock 594MHz) and
> > another one is 4K 30Hz (pixelclock 297MHz).
> >
> > The issue is gone after setting "power_dpm_force_performance_level" to
> > "high". Following the indication, we found that the issue occurs when
> > sclk is too low.
> >
> > So resolve the issue by disabling sclk switching when there are two
> > monitors requires high pixelclock (> 297MHz).
> >
> > v2:
> >  - Only apply the fix to Oland.
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>
> A gentle ping...

Applied.  Thanks for the reminder.

Alex


>
> > ---
> >  drivers/gpu/drm/radeon/radeon.h    | 1 +
> >  drivers/gpu/drm/radeon/radeon_pm.c | 8 ++++++++
> >  drivers/gpu/drm/radeon/si_dpm.c    | 3 +++
> >  3 files changed, 12 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
> > index 42281fce552e6..56ed5634cebef 100644
> > --- a/drivers/gpu/drm/radeon/radeon.h
> > +++ b/drivers/gpu/drm/radeon/radeon.h
> > @@ -1549,6 +1549,7 @@ struct radeon_dpm {
> >         void                    *priv;
> >         u32                     new_active_crtcs;
> >         int                     new_active_crtc_count;
> > +       int                     high_pixelclock_count;
> >         u32                     current_active_crtcs;
> >         int                     current_active_crtc_count;
> >         bool single_display;
> > diff --git a/drivers/gpu/drm/radeon/radeon_pm.c b/drivers/gpu/drm/radeon/radeon_pm.c
> > index 0c1950f4e146f..3861c0b98fcf3 100644
> > --- a/drivers/gpu/drm/radeon/radeon_pm.c
> > +++ b/drivers/gpu/drm/radeon/radeon_pm.c
> > @@ -1767,6 +1767,7 @@ static void radeon_pm_compute_clocks_dpm(struct radeon_device *rdev)
> >         struct drm_device *ddev = rdev->ddev;
> >         struct drm_crtc *crtc;
> >         struct radeon_crtc *radeon_crtc;
> > +       struct radeon_connector *radeon_connector;
> >
> >         if (!rdev->pm.dpm_enabled)
> >                 return;
> > @@ -1776,6 +1777,7 @@ static void radeon_pm_compute_clocks_dpm(struct radeon_device *rdev)
> >         /* update active crtc counts */
> >         rdev->pm.dpm.new_active_crtcs = 0;
> >         rdev->pm.dpm.new_active_crtc_count = 0;
> > +       rdev->pm.dpm.high_pixelclock_count = 0;
> >         if (rdev->num_crtc && rdev->mode_info.mode_config_initialized) {
> >                 list_for_each_entry(crtc,
> >                                     &ddev->mode_config.crtc_list, head) {
> > @@ -1783,6 +1785,12 @@ static void radeon_pm_compute_clocks_dpm(struct radeon_device *rdev)
> >                         if (crtc->enabled) {
> >                                 rdev->pm.dpm.new_active_crtcs |= (1 << radeon_crtc->crtc_id);
> >                                 rdev->pm.dpm.new_active_crtc_count++;
> > +                               if (!radeon_crtc->connector)
> > +                                       continue;
> > +
> > +                               radeon_connector = to_radeon_connector(radeon_crtc->connector);
> > +                               if (radeon_connector->pixelclock_for_modeset > 297000)
> > +                                       rdev->pm.dpm.high_pixelclock_count++;
> >                         }
> >                 }
> >         }
> > diff --git a/drivers/gpu/drm/radeon/si_dpm.c b/drivers/gpu/drm/radeon/si_dpm.c
> > index 9186095518047..3cc2b96a7f368 100644
> > --- a/drivers/gpu/drm/radeon/si_dpm.c
> > +++ b/drivers/gpu/drm/radeon/si_dpm.c
> > @@ -2979,6 +2979,9 @@ static void si_apply_state_adjust_rules(struct radeon_device *rdev,
> >                     (rdev->pdev->device == 0x6605)) {
> >                         max_sclk = 75000;
> >                 }
> > +
> > +               if (rdev->pm.dpm.high_pixelclock_count > 1)
> > +                       disable_sclk_switching = true;
> >         }
> >
> >         if (rps->vce_active) {
> > --
> > 2.30.2
> >