Message-ID: <1428d7bff3fb755c5bce8f50d725ae0e2b2438de.camel@aol.com>
Date: Sat, 16 Aug 2025 14:55:22 +0100
From: Ruben Wauters <rubenru09@....com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard	
 <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
	 <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Ingo Molnar	
 <mingo@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Jani Nikula	
 <jani.nikula@...el.com>, Jocelyn Falempe <jfalempe@...hat.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/gud: Replace simple display pipe with DRM atomic
 helpers

On Sat, 2025-08-16 at 10:57 +0100, Ruben Wauters wrote:
> The simple display pipe is obsolete and the atomic helpers allow for
> more control over the rendering process. As such, this patch replaces
> the old simple display pipe system with the newer atomic helpers.
> 
> As the code is mainly the same, merely replaced with the new atomic
> system, there should be no change in functionality.
> 
> Signed-off-by: Ruben Wauters <rubenru09@....com>
> ---
> I have been able to test this now, having obtained the hardware, and
> it
> works fine, though some other unrelated issues have popped up, which
> I
> shall try and debug and address in other patches.
> 
> v2 changes:
> - address review comments by reorganising gud_probe()
> ---
>  drivers/gpu/drm/gud/gud_connector.c | 24 +++++-----
>  drivers/gpu/drm/gud/gud_drv.c       | 52 +++++++++++++++++-----
>  drivers/gpu/drm/gud/gud_internal.h  | 13 +++---
>  drivers/gpu/drm/gud/gud_pipe.c      | 69 ++++++++++++++++++++-------
> --
>  4 files changed, 108 insertions(+), 50 deletions(-)
> 
> diff --git a/drivers/gpu/drm/gud/gud_connector.c
> b/drivers/gpu/drm/gud/gud_connector.c
> index 0f07d77c5d52..75f404ec08b4 100644
> --- a/drivers/gpu/drm/gud/gud_connector.c
> +++ b/drivers/gpu/drm/gud/gud_connector.c
> @@ -607,13 +607,16 @@ int gud_connector_fill_properties(struct
> drm_connector_state *connector_state,
>  	return gconn->num_properties;
>  }
>  
> +static const struct drm_encoder_funcs
> gud_drm_simple_encoder_funcs_cleanup = {
> +	.destroy = drm_encoder_cleanup,
> +};
> +
>  static int gud_connector_create(struct gud_device *gdrm, unsigned
> int index,
>  				struct gud_connector_descriptor_req
> *desc)
>  {
>  	struct drm_device *drm = &gdrm->drm;
>  	struct gud_connector *gconn;
>  	struct drm_connector *connector;
> -	struct drm_encoder *encoder;
>  	int ret, connector_type;
>  	u32 flags;
>  
> @@ -681,20 +684,13 @@ static int gud_connector_create(struct
> gud_device *gdrm, unsigned int index,
>  		return ret;
>  	}
>  
> -	/* The first connector is attached to the existing simple
> pipe encoder */
> -	if (!connector->index) {
> -		encoder = &gdrm->pipe.encoder;
> -	} else {
> -		encoder = &gconn->encoder;
> -
> -		ret = drm_simple_encoder_init(drm, encoder,
> DRM_MODE_ENCODER_NONE);
> -		if (ret)
> -			return ret;
> -
> -		encoder->possible_crtcs = 1;
> -	}
> +	gdrm->encoder.possible_crtcs = drm_crtc_mask(&gdrm->crtc);
> +	ret = drm_encoder_init(drm, &gdrm->encoder,
> &gud_drm_simple_encoder_funcs_cleanup,
> +			       DRM_MODE_ENCODER_NONE, NULL);
> +	if (ret)
> +		return ret;
>  
> -	return drm_connector_attach_encoder(connector, encoder);
> +	return drm_connector_attach_encoder(connector, &gdrm-
> >encoder);
>  }
>  
>  int gud_get_connectors(struct gud_device *gdrm)
> diff --git a/drivers/gpu/drm/gud/gud_drv.c
> b/drivers/gpu/drm/gud/gud_drv.c
> index 5385a2126e45..65c3a83c4037 100644
> --- a/drivers/gpu/drm/gud/gud_drv.c
> +++ b/drivers/gpu/drm/gud/gud_drv.c
> @@ -16,6 +16,7 @@
>  #include <drm/clients/drm_client_setup.h>
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_blend.h>
> +#include <drm/drm_crtc_helper.h>
>  #include <drm/drm_damage_helper.h>
>  #include <drm/drm_debugfs.h>
>  #include <drm/drm_drv.h>
> @@ -289,7 +290,7 @@ static int gud_get_properties(struct gud_device
> *gdrm)
>  			 * but mask out any additions on future
> devices.
>  			 */
>  			val &= GUD_ROTATION_MASK;
> -			ret =
> drm_plane_create_rotation_property(&gdrm->pipe.plane,
> +			ret =
> drm_plane_create_rotation_property(&gdrm->plane,
>  								
> DRM_MODE_ROTATE_0, val);
>  			break;
>  		default:
> @@ -338,10 +339,30 @@ static int gud_stats_debugfs(struct seq_file
> *m, void *data)
>  	return 0;
>  }
>  
> -static const struct drm_simple_display_pipe_funcs gud_pipe_funcs = {
> -	.check      = gud_pipe_check,
> -	.update	    = gud_pipe_update,
> -	DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS
> +static const struct drm_crtc_helper_funcs gud_crtc_helper_funcs = {
> +	.atomic_check = drm_crtc_helper_atomic_check
> +};
> +
> +static const struct drm_crtc_funcs gud_crtc_funcs = {
> +	.reset = drm_atomic_helper_crtc_reset,
> +	.destroy = drm_crtc_cleanup,
> +	.set_config = drm_atomic_helper_set_config,
> +	.page_flip = drm_atomic_helper_page_flip,
> +	.atomic_duplicate_state =
> drm_atomic_helper_crtc_duplicate_state,
> +	.atomic_destroy_state =
> drm_atomic_helper_crtc_destroy_state,
> +};
> +
> +static const struct drm_plane_helper_funcs gud_plane_helper_funcs =
> {
> +	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
> +	.atomic_check = gud_plane_atomic_check,
> +	.atomic_update = gud_plane_atomic_update,
> +};
> +
> +static const struct drm_plane_funcs gud_plane_funcs = {
> +	.update_plane = drm_atomic_helper_update_plane,
> +	.disable_plane = drm_atomic_helper_disable_plane,
> +	.destroy = drm_plane_cleanup,
> +	DRM_GEM_SHADOW_PLANE_FUNCS,
>  };
>  
>  static const struct drm_mode_config_funcs gud_mode_config_funcs = {
> @@ -350,7 +371,7 @@ static const struct drm_mode_config_funcs
> gud_mode_config_funcs = {
>  	.atomic_commit = drm_atomic_helper_commit,
>  };
>  
> -static const u64 gud_pipe_modifiers[] = {
> +static const u64 gud_plane_modifiers[] = {
>  	DRM_FORMAT_MOD_LINEAR,
>  	DRM_FORMAT_MOD_INVALID
>  };
> @@ -567,12 +588,17 @@ static int gud_probe(struct usb_interface
> *intf, const struct usb_device_id *id)
>  			return -ENOMEM;
>  	}
>  
> -	ret = drm_simple_display_pipe_init(drm, &gdrm->pipe,
> &gud_pipe_funcs,
> -					   formats, num_formats,
> -					   gud_pipe_modifiers,
> NULL);
> +	ret = drm_universal_plane_init(drm, &gdrm->plane, 0,
> +				       &gud_plane_funcs,
> +				       formats, num_formats,
> +				       gud_plane_modifiers,
> +				       DRM_PLANE_TYPE_PRIMARY,
> NULL);
>  	if (ret)
>  		return ret;
>  
> +	drm_plane_helper_add(&gdrm->plane, &gud_plane_helper_funcs);
> +	drm_plane_enable_fb_damage_clips(&gdrm->plane);
> +
>  	devm_kfree(dev, formats);
>  	devm_kfree(dev, formats_dev);
>  
> @@ -582,7 +608,13 @@ static int gud_probe(struct usb_interface *intf,
> const struct usb_device_id *id)
>  		return ret;
>  	}
>  
> -	drm_plane_enable_fb_damage_clips(&gdrm->pipe.plane);
> +	ret = drm_crtc_init_with_planes(drm, &gdrm->crtc, &gdrm-
> >plane, NULL,
> +					&gud_crtc_funcs, NULL);
> +
> +	if (ret)
> +		return ret;
> +
> +	drm_crtc_helper_add(&gdrm->crtc, &gud_crtc_helper_funcs);
>  
>  	ret = gud_get_connectors(gdrm);
>  	if (ret) {
> diff --git a/drivers/gpu/drm/gud/gud_internal.h
> b/drivers/gpu/drm/gud/gud_internal.h
> index d6fb25388722..6152a9b5da43 100644
> --- a/drivers/gpu/drm/gud/gud_internal.h
> +++ b/drivers/gpu/drm/gud/gud_internal.h
> @@ -15,7 +15,9 @@
>  
>  struct gud_device {
>  	struct drm_device drm;
> -	struct drm_simple_display_pipe pipe;
> +	struct drm_plane plane;
> +	struct drm_crtc crtc;
> +	struct drm_encoder encoder;
>  	struct work_struct work;
>  	u32 flags;
>  	const struct drm_format_info *xrgb8888_emulation_format;
> @@ -62,11 +64,10 @@ int gud_usb_set_u8(struct gud_device *gdrm, u8
> request, u8 val);
>  
>  void gud_clear_damage(struct gud_device *gdrm);
>  void gud_flush_work(struct work_struct *work);
> -int gud_pipe_check(struct drm_simple_display_pipe *pipe,
> -		   struct drm_plane_state *new_plane_state,
> -		   struct drm_crtc_state *new_crtc_state);
> -void gud_pipe_update(struct drm_simple_display_pipe *pipe,
> -		     struct drm_plane_state *old_state);
> +int gud_plane_atomic_check(struct drm_plane *plane,
> +			   struct drm_atomic_state *state);
> +void gud_plane_atomic_update(struct drm_plane *plane,
> +			     struct drm_atomic_state *atomic_state);
>  int gud_connector_fill_properties(struct drm_connector_state
> *connector_state,
>  				  struct gud_property_req
> *properties);
>  int gud_get_connectors(struct gud_device *gdrm);
> diff --git a/drivers/gpu/drm/gud/gud_pipe.c
> b/drivers/gpu/drm/gud/gud_pipe.c
> index 8d548d08f127..6a0e6234224a 100644
> --- a/drivers/gpu/drm/gud/gud_pipe.c
> +++ b/drivers/gpu/drm/gud/gud_pipe.c
> @@ -451,14 +451,15 @@ static void gud_fb_handle_damage(struct
> gud_device *gdrm, struct drm_framebuffer
>  	gud_flush_damage(gdrm, fb, src, !fb->obj[0]->import_attach,
> damage);
>  }
>  
> -int gud_pipe_check(struct drm_simple_display_pipe *pipe,
> -		   struct drm_plane_state *new_plane_state,
> -		   struct drm_crtc_state *new_crtc_state)
> +int gud_plane_atomic_check(struct drm_plane *plane,
> +			   struct drm_atomic_state *state)
>  {
> -	struct gud_device *gdrm = to_gud_device(pipe->crtc.dev);
> -	struct drm_plane_state *old_plane_state = pipe->plane.state;
> -	const struct drm_display_mode *mode = &new_crtc_state->mode;
> -	struct drm_atomic_state *state = new_plane_state->state;
> +	struct gud_device *gdrm = to_gud_device(plane->dev);
> +	struct drm_plane_state *old_plane_state =
> drm_atomic_get_old_plane_state(state, plane);
> +	struct drm_plane_state *new_plane_state =
> drm_atomic_get_new_plane_state(state, plane);
> +	struct drm_crtc *crtc = new_plane_state->crtc;
> +	struct drm_crtc_state *crtc_state;
> +	const struct drm_display_mode *mode;
>  	struct drm_framebuffer *old_fb = old_plane_state->fb;
>  	struct drm_connector_state *connector_state = NULL;
>  	struct drm_framebuffer *fb = new_plane_state->fb;
> @@ -472,17 +473,35 @@ int gud_pipe_check(struct
> drm_simple_display_pipe *pipe,
>  	if (WARN_ON_ONCE(!fb))
>  		return -EINVAL;
>  
> +	if (WARN_ON_ONCE(!crtc))
> +		return -EINVAL;
> +
> +	crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
> +
> +	mode = &crtc_state->mode;
> +
> +	ret = drm_atomic_helper_check_plane_state(new_plane_state,
> crtc_state,
> +						 
> DRM_PLANE_NO_SCALING,
> +						 
> DRM_PLANE_NO_SCALING,
> +						  false, false);
> +
> +	if (ret)
> +		return ret;
> +
> +	if (!new_plane_state->visible)
> +		return 0;
> +
>  	if (old_plane_state->rotation != new_plane_state->rotation)
> -		new_crtc_state->mode_changed = true;
> +		crtc_state->mode_changed = true;
>  
>  	if (old_fb && old_fb->format != format)
> -		new_crtc_state->mode_changed = true;
> +		crtc_state->mode_changed = true;
>  
> -	if (!new_crtc_state->mode_changed && !new_crtc_state-
> >connectors_changed)
> +	if (!crtc_state->mode_changed && !crtc_state-
> >connectors_changed)
>  		return 0;
>  
>  	/* Only one connector is supported */
> -	if (hweight32(new_crtc_state->connector_mask) != 1)
> +	if (hweight32(crtc_state->connector_mask) != 1)
>  		return -EINVAL;
>  
>  	if (format->format == DRM_FORMAT_XRGB8888 && gdrm-
> >xrgb8888_emulation_format)
> @@ -500,7 +519,7 @@ int gud_pipe_check(struct drm_simple_display_pipe
> *pipe,
>  	if (!connector_state) {
>  		struct drm_connector_list_iter conn_iter;
>  
> -		drm_connector_list_iter_begin(pipe->crtc.dev,
> &conn_iter);
> +		drm_connector_list_iter_begin(plane->dev,
> &conn_iter);
>  		drm_for_each_connector_iter(connector, &conn_iter) {
>  			if (connector->state->crtc) {
>  				connector_state = connector->state;
> @@ -567,16 +586,19 @@ int gud_pipe_check(struct
> drm_simple_display_pipe *pipe,
>  	return ret;
>  }
>  
> -void gud_pipe_update(struct drm_simple_display_pipe *pipe,
> -		     struct drm_plane_state *old_state)
> +void gud_plane_atomic_update(struct drm_plane *plane,
> +			     struct drm_atomic_state *atomic_state)
>  {
> -	struct drm_device *drm = pipe->crtc.dev;
> +	struct drm_device *drm = plane->dev;
>  	struct gud_device *gdrm = to_gud_device(drm);
> -	struct drm_plane_state *state = pipe->plane.state;
> -	struct drm_shadow_plane_state *shadow_plane_state =
> to_drm_shadow_plane_state(state);
> -	struct drm_framebuffer *fb = state->fb;
> -	struct drm_crtc *crtc = &pipe->crtc;
> +	struct drm_plane_state *old_state =
> drm_atomic_get_old_plane_state(atomic_state, plane);
> +	struct drm_plane_state *new_state =
> drm_atomic_get_new_plane_state(atomic_state, plane);
> +	struct drm_shadow_plane_state *shadow_plane_state =
> to_drm_shadow_plane_state(new_state);
> +	struct drm_framebuffer *fb = new_state->fb;
> +	struct drm_crtc *crtc = new_state->crtc;
>  	struct drm_rect damage;
> +	struct drm_rect dst_clip;
> +	struct drm_atomic_helper_damage_iter iter;
>  	int ret, idx;
>  
>  	if (crtc->state->mode_changed || !crtc->state->enable) {
> @@ -611,8 +633,15 @@ void gud_pipe_update(struct
> drm_simple_display_pipe *pipe,
>  	if (ret)
>  		goto ctrl_disable;
>  
> -	if (drm_atomic_helper_damage_merged(old_state, state,
> &damage))
> +	drm_atomic_helper_damage_iter_init(&iter, old_state,
> new_state);
> +	drm_atomic_for_each_plane_damage(&iter, &damage) {
> +		dst_clip = new_state->dst;
> +
> +		if (!drm_rect_intersect(&dst_clip, &damage))
> +			continue;
> +
>  		gud_fb_handle_damage(gdrm, fb, &shadow_plane_state-
> >data[0], &damage);
> +	}
>  
>  	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
>  
My apologies, I appear to have typo'd the mailing list, I am replying
to ensure that it is included here

Ruben

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