From 70b8c6f7b061b4a362775cc7a724eee83175918b Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Wed, 19 Feb 2025 18:02:39 +0200 Subject: [PATCH] drm/atomic: Filter out redundant DPMS calls MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit de93ddf88088f7624b589d0ff3af9effb87e8f3b upstream. Video players (eg. mpv) do periodic XResetScreenSaver() calls to keep the screen on while the video playing. The modesetting ddx plumbs these straight through into the kernel as DPMS setproperty ioctls, without any filtering whatsoever. When implemented via atomic these end up as empty commits on the crtc (which will nonetheless take one full frame), which leads to a dropped frame every time XResetScreenSaver() is called. Let's just filter out redundant DPMS property changes in the kernel to avoid this issue. v2: Explain the resulting commits a bit better (Sima) Document the behaviour in uapi docs (Sima) Cc: stable@vger.kernel.org Testcase: igt/kms_flip/flip-vs-dpms-on-nop Reviewed-by: Simona Vetter Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20250219160239.17502-1-ville.syrjala@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_atomic_uapi.c | 4 ++++ drivers/gpu/drm/drm_connector.c | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c index fb646b12af042..476357fb5c74a 100644 --- a/drivers/gpu/drm/drm_atomic_uapi.c +++ b/drivers/gpu/drm/drm_atomic_uapi.c @@ -964,6 +964,10 @@ int drm_atomic_connector_commit_dpms(struct drm_atomic_state *state, if (mode != DRM_MODE_DPMS_ON) mode = DRM_MODE_DPMS_OFF; + + if (connector->dpms == mode) + goto out; + connector->dpms = mode; crtc = connector->state->crtc; diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index 1140292820bb1..fff2038e98035 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -980,6 +980,10 @@ static const struct drm_prop_enum_list dp_colorspaces[] = { * callback. For atomic drivers the remapping to the "ACTIVE" property is * implemented in the DRM core. * + * On atomic drivers any DPMS setproperty ioctl where the value does not + * change is completely skipped, otherwise a full atomic commit will occur. + * On legacy drivers the exact behavior is driver specific. + * * Note that this property cannot be set through the MODE_ATOMIC ioctl, * userspace must use "ACTIVE" on the CRTC instead. * -- 2.47.3