From: Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: apldrm: switch to drm_atomic_helper_commit_tail_rpm()
To: Tobias Heider <tobias.heider@stusta.de>
Cc: tech@openbsd.org, kettenis@openbsd.org, jsg@openbsd.org
Date: Tue, 25 Aug 2026 15:50:37 +0200

> Date: Tue, 25 Aug 2026 13:29:03 +0200
> From: Tobias Heider <tobias.heider@stusta.de>
> 
> Hi,
> 
> I was investigating high latency for the display on my m2 macbook air
> and traced it back to drm_atomic_helper_wait_for_flip_done() in our
> custom dcp_atomic_commit_tail().
> 
> Looking closer at the asahi tree it turns out they switched back to
> the generic drm_atomic_helper_commit_tail_rpm() in
>  https://github.com/AsahiLinux/linux/commit/bd8ce96f6e76b98940352b18fe735a7943471ed7
> 
> I propose we do the same. With this the graphical interface feels noticably
> snappier.
> 
> ok?

ok kettenis@

> diff /usr/src
> path + /usr/src
> commit - c9c6a4136a24cbff385a3cfe930ee8cf183d41a5
> blob - ffe2d92a4994103f8db5afe7bcd395ea70067d2b
> file + sys/dev/pci/drm/apple/apple_drv.c
> --- sys/dev/pci/drm/apple/apple_drv.c
> +++ sys/dev/pci/drm/apple/apple_drv.c
> @@ -237,26 +237,6 @@ static void apple_crtc_atomic_begin(struct drm_crtc *c
>  	}
>  }
>  
> -static void dcp_atomic_commit_tail(struct drm_atomic_state *old_state)
> -{
> -	struct drm_device *dev = old_state->dev;
> -
> -	drm_atomic_helper_commit_modeset_disables(dev, old_state);
> -
> -	drm_atomic_helper_commit_modeset_enables(dev, old_state);
> -
> -	drm_atomic_helper_commit_planes(dev, old_state,
> -					DRM_PLANE_COMMIT_ACTIVE_ONLY);
> -
> -	drm_atomic_helper_fake_vblank(old_state);
> -
> -	drm_atomic_helper_commit_hw_done(old_state);
> -
> -	drm_atomic_helper_wait_for_flip_done(dev, old_state);
> -
> -	drm_atomic_helper_cleanup_planes(dev, old_state);
> -}
> -
>  static void apple_crtc_cleanup(struct drm_crtc *crtc)
>  {
>  	drm_crtc_cleanup(crtc);
> @@ -279,7 +259,7 @@ static const struct drm_mode_config_funcs apple_mode_c
>  };
>  
>  static const struct drm_mode_config_helper_funcs apple_mode_config_helpers = {
> -	.atomic_commit_tail	= dcp_atomic_commit_tail,
> +	.atomic_commit_tail	= drm_atomic_helper_commit_tail_rpm,
>  };
>  
>  static void appledrm_connector_cleanup(struct drm_connector *connector)
> 
>