Re: [PATCH v3 3/6] drm: introduce drm_mode_config.atomic_async_page_flip_not_supported

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Sep 29, 2022 at 06:43:42PM +0000, Simon Ser wrote:
> This new field indicates whether the driver has the necessary logic
> to support async page-flips via the atomic uAPI. This is leveraged by
> the next commit to allow user-space to use this functionality.
> 
> All atomic drivers setting drm_mode_config.async_page_flip are updated
> to also set drm_mode_config.atomic_async_page_flip_not_supported. We
> will gradually check and update these drivers to properly handle
> drm_crtc_state.async_flip in their atomic logic.
> 
> The goal of this negative flag is the same as
> fb_modifiers_not_supported: we want to eventually get rid of all
> drivers missing atomic support for async flips. New drivers should not
> set this flag, instead they should support atomic async flips (if
> they support async flips at all). IOW, we don't want more drivers
> with async flip support for legacy but not atomic.
> 
> v2: only set the flag on atomic drivers (remove it on amdgpu DCE and
> on radeon)
> 
> Signed-off-by: Simon Ser <contact@emersion.fr>
> Reviewed-by: André Almeida <andrealmeid@igalia.com>
> Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Joshua Ashton <joshua@froggi.es>
> Cc: Melissa Wen <mwen@igalia.com>
> Cc: Harry Wentland <hwentlan@amd.com>
> Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  1 +
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c      |  1 +
>  drivers/gpu/drm/i915/display/intel_display.c      |  1 +
>  drivers/gpu/drm/nouveau/nouveau_display.c         |  1 +
>  drivers/gpu/drm/vc4/vc4_kms.c                     |  1 +
>  include/drm/drm_mode_config.h                     | 11 +++++++++++
>  6 files changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 44235345fd57..7500e82cf06a 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3808,6 +3808,7 @@ static int amdgpu_dm_mode_config_init(struct amdgpu_device *adev)
>  		adev_to_drm(adev)->mode_config.prefer_shadow = 1;
>  	/* indicates support for immediate flip */
>  	adev_to_drm(adev)->mode_config.async_page_flip = true;
> +	adev_to_drm(adev)->mode_config.atomic_async_page_flip_not_supported = true;

The flag polarity seems weird. Why opt out and not opt in?

>  
>  	adev_to_drm(adev)->mode_config.fb_base = adev->gmc.aper_base;
>  
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
> index f7e7f4e919c7..ffb3a2fa797f 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
> @@ -639,6 +639,7 @@ static int atmel_hlcdc_dc_modeset_init(struct drm_device *dev)
>  	dev->mode_config.max_height = dc->desc->max_height;
>  	dev->mode_config.funcs = &mode_config_funcs;
>  	dev->mode_config.async_page_flip = true;
> +	dev->mode_config.atomic_async_page_flip_not_supported = true;
>  
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 40fbf8a296e2..e025b3499c9d 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -8621,6 +8621,7 @@ static void intel_mode_config_init(struct drm_i915_private *i915)
>  	mode_config->helper_private = &intel_mode_config_funcs;
>  
>  	mode_config->async_page_flip = HAS_ASYNC_FLIPS(i915);
> +	mode_config->atomic_async_page_flip_not_supported = true;
>  
>  	/*
>  	 * Maximum framebuffer dimensions, chosen to match
> diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
> index a2f5df568ca5..2b5c4f24aedd 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_display.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_display.c
> @@ -699,6 +699,7 @@ nouveau_display_create(struct drm_device *dev)
>  		dev->mode_config.async_page_flip = false;
>  	else
>  		dev->mode_config.async_page_flip = true;
> +	dev->mode_config.atomic_async_page_flip_not_supported = true;
>  
>  	drm_kms_helper_poll_init(dev);
>  	drm_kms_helper_poll_disable(dev);
> diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> index 4419e810103d..3fe59c6b2cf0 100644
> --- a/drivers/gpu/drm/vc4/vc4_kms.c
> +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> @@ -1047,6 +1047,7 @@ int vc4_kms_load(struct drm_device *dev)
>  	dev->mode_config.helper_private = &vc4_mode_config_helpers;
>  	dev->mode_config.preferred_depth = 24;
>  	dev->mode_config.async_page_flip = true;
> +	dev->mode_config.atomic_async_page_flip_not_supported = true;
>  
>  	ret = vc4_ctm_obj_init(vc4);
>  	if (ret)
> diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> index 6b5e01295348..1b535d94f2f4 100644
> --- a/include/drm/drm_mode_config.h
> +++ b/include/drm/drm_mode_config.h
> @@ -917,6 +917,17 @@ struct drm_mode_config {
>  	 */
>  	bool async_page_flip;
>  
> +	/**
> +	 * @atomic_async_page_flip_not_supported:
> +	 *
> +	 * If true, the driver does not support async page-flips with the
> +	 * atomic uAPI. This is only used by old drivers which haven't yet
> +	 * accomodated for &drm_crtc_state.async_flip in their atomic logic,
> +	 * even if they have &drm_mode_config.async_page_flip set to true.
> +	 * New drivers shall not set this flag.
> +	 */
> +	bool atomic_async_page_flip_not_supported;
> +
>  	/**
>  	 * @fb_modifiers_not_supported:
>  	 *
> -- 
> 2.37.3
> 

-- 
Ville Syrjälä
Intel