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Message-ID: <CADnq5_MGhFTUOafo_Prjxgek7ufP-9uo59a+_R0=DKZBQayX0Q@mail.gmail.com>
Date: Thu, 29 Apr 2021 16:06:35 -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 <linux-kernel@...r.kernel.org>,
"open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
"open list:RADEON and AMDGPU DRM DRIVERS"
<amd-gfx@...ts.freedesktop.org>
Subject: Re: [PATCH] drm/radeon/dpm: Disable sclk switching when two 4K 60Hz
monitors are connected
On Thu, Apr 29, 2021 at 9:40 AM Kai-Heng Feng
<kai.heng.feng@...onical.com> wrote:
>
> Screen flickers rapidly when two 4K 60Hz monitors are connected to an
> Oland card. 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 lead, we found that the issue only occurs when
> sclk is too low.
>
> So resolve the issue by disabling sclk switching when there are two
> monitors that requires high pixelclock (> 297MHz).
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> 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..be6fa3257d1bc 100644
> --- a/drivers/gpu/drm/radeon/si_dpm.c
> +++ b/drivers/gpu/drm/radeon/si_dpm.c
> @@ -2995,6 +2995,9 @@ static void si_apply_state_adjust_rules(struct radeon_device *rdev,
> ni_dpm_vblank_too_short(rdev))
> disable_mclk_switching = true;
>
> + if (rdev->pm.dpm.high_pixelclock_count > 1)
> + disable_sclk_switching = true;
> +
I would suggest limiting this to just Oland.
Alex
> if (rps->vclk || rps->dclk) {
> disable_mclk_switching = true;
> disable_sclk_switching = true;
> --
> 2.30.2
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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