Re: [PATCH] drm/plane-helper: Add a drm_plane_helper_atomic_check() helper

[Ville Syrjälä]

On Mon, Sep 12, 2022 at 01:05:45PM +0200, Thomas Zimmermann wrote:
> Hi
> 
> Am 12.09.22 um 12:40 schrieb Ville Syrjälä:
> > On Mon, Sep 12, 2022 at 12:15:22PM +0200, Javier Martinez Canillas wrote:
> >> Provides a default plane state check handler for primary planes that are a
> >> fullscreen scanout buffer and whose state scale and position can't change.
> >>
> >> There are some drivers that duplicate this logic in their helpers, such as
> >> simpledrm and ssd130x. Factor out this common code into a plane helper and
> >> make drivers use it.
> >>
> >> Suggested-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> >> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> >> ---
> >>
> >>   drivers/gpu/drm/drm_plane_helper.c | 29 +++++++++++++++++++++++++++++
> >>   drivers/gpu/drm/solomon/ssd130x.c  | 18 +-----------------
> >>   drivers/gpu/drm/tiny/simpledrm.c   | 25 +------------------------
> >>   include/drm/drm_plane_helper.h     |  2 ++
> >>   4 files changed, 33 insertions(+), 41 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c
> >> index c7785967f5bf..fb41eee74693 100644
> >> --- a/drivers/gpu/drm/drm_plane_helper.c
> >> +++ b/drivers/gpu/drm/drm_plane_helper.c
> >> @@ -278,3 +278,32 @@ void drm_plane_helper_destroy(struct drm_plane *plane)
> >>   	kfree(plane);
> >>   }
> >>   EXPORT_SYMBOL(drm_plane_helper_destroy);
> >> +
> >> +/**
> >> + * drm_plane_helper_atomic_check() - Helper to check primary planes states
> >> + * @plane: plane to check
> >> + * @new_state: plane state to check
> > 
> > That is not a plane state. Also should s/new_// since it's just
> > the overall atomic state thing rather than some new or old state.
> 
> Using only 'state' is non-intuitive and has lead to bugs where sub-state 
> was retrieved from the wrong state information. So we've been using 
> 'new_state' and 'old_state' explicitly in several places now.

There is no old or new drm_atomic_state. It contains both.

> 
> Best regards
> Thomas
> 
> > 
> >> + *
> >> + * Provides a default plane state check handler for primary planes whose atomic
> >> + * state scale and position is not expected to change because the primary plane
> >> + * is always a fullscreen scanout buffer.
> >> + *
> >> + * RETURNS:
> >> + * Zero on success, or an errno code otherwise.
> >> + */
> >> +int drm_plane_helper_atomic_check(struct drm_plane *plane,
> >> +				  struct drm_atomic_state *new_state)
> >> +{
> >> +	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(new_state, plane);
> >> +	struct drm_crtc *new_crtc = new_plane_state->crtc;
> >> +	struct drm_crtc_state *new_crtc_state = NULL;
> >> +
> >> +	if (new_crtc)
> >> +		new_crtc_state = drm_atomic_get_new_crtc_state(new_state, new_crtc);
> >> +
> >> +	return drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
> >> +						   DRM_PLANE_NO_SCALING,
> >> +						   DRM_PLANE_NO_SCALING,
> >> +						   false, false);
> >> +}
> >> +EXPORT_SYMBOL(drm_plane_helper_atomic_check);
> >> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
> >> index 79e8e2017c68..28cf9c87f86d 100644
> >> --- a/drivers/gpu/drm/solomon/ssd130x.c
> >> +++ b/drivers/gpu/drm/solomon/ssd130x.c
> >> @@ -565,22 +565,6 @@ static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb, const struct iosys_m
> >>   	return ret;
> >>   }
> >>   
> >> -static int ssd130x_primary_plane_helper_atomic_check(struct drm_plane *plane,
> >> -						     struct drm_atomic_state *new_state)
> >> -{
> >> -	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(new_state, plane);
> >> -	struct drm_crtc *new_crtc = new_plane_state->crtc;
> >> -	struct drm_crtc_state *new_crtc_state = NULL;
> >> -
> >> -	if (new_crtc)
> >> -		new_crtc_state = drm_atomic_get_new_crtc_state(new_state, new_crtc);
> >> -
> >> -	return drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
> >> -						   DRM_PLANE_NO_SCALING,
> >> -						   DRM_PLANE_NO_SCALING,
> >> -						   false, false);
> >> -}
> >> -
> >>   static void ssd130x_primary_plane_helper_atomic_update(struct drm_plane *plane,
> >>   						       struct drm_atomic_state *old_state)
> >>   {
> >> @@ -623,7 +607,7 @@ static void ssd130x_primary_plane_helper_atomic_disable(struct drm_plane *plane,
> >>   
> >>   static const struct drm_plane_helper_funcs ssd130x_primary_plane_helper_funcs = {
> >>   	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
> >> -	.atomic_check = ssd130x_primary_plane_helper_atomic_check,
> >> +	.atomic_check = drm_plane_helper_atomic_check,
> >>   	.atomic_update = ssd130x_primary_plane_helper_atomic_update,
> >>   	.atomic_disable = ssd130x_primary_plane_helper_atomic_disable,
> >>   };
> >> diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
> >> index 777ccd250871..ea5b3239a659 100644
> >> --- a/drivers/gpu/drm/tiny/simpledrm.c
> >> +++ b/drivers/gpu/drm/tiny/simpledrm.c
> >> @@ -469,29 +469,6 @@ static const uint64_t simpledrm_primary_plane_format_modifiers[] = {
> >>   	DRM_FORMAT_MOD_INVALID
> >>   };
> >>   
> >> -static int simpledrm_primary_plane_helper_atomic_check(struct drm_plane *plane,
> >> -						       struct drm_atomic_state *new_state)
> >> -{
> >> -	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(new_state, plane);
> >> -	struct drm_crtc *new_crtc = new_plane_state->crtc;
> >> -	struct drm_crtc_state *new_crtc_state = NULL;
> >> -	int ret;
> >> -
> >> -	if (new_crtc)
> >> -		new_crtc_state = drm_atomic_get_new_crtc_state(new_state, new_crtc);
> >> -
> >> -	ret = drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
> >> -						  DRM_PLANE_NO_SCALING,
> >> -						  DRM_PLANE_NO_SCALING,
> >> -						  false, false);
> >> -	if (ret)
> >> -		return ret;
> >> -	else if (!new_plane_state->visible)
> >> -		return 0;
> >> -
> >> -	return 0;
> >> -}
> >> -
> >>   static void simpledrm_primary_plane_helper_atomic_update(struct drm_plane *plane,
> >>   							 struct drm_atomic_state *old_state)
> >>   {
> >> @@ -543,7 +520,7 @@ static void simpledrm_primary_plane_helper_atomic_disable(struct drm_plane *plan
> >>   
> >>   static const struct drm_plane_helper_funcs simpledrm_primary_plane_helper_funcs = {
> >>   	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
> >> -	.atomic_check = simpledrm_primary_plane_helper_atomic_check,
> >> +	.atomic_check = drm_plane_helper_atomic_check,
> >>   	.atomic_update = simpledrm_primary_plane_helper_atomic_update,
> >>   	.atomic_disable = simpledrm_primary_plane_helper_atomic_disable,
> >>   };
> >> diff --git a/include/drm/drm_plane_helper.h b/include/drm/drm_plane_helper.h
> >> index 1781fab24dd6..7ba414655d69 100644
> >> --- a/include/drm/drm_plane_helper.h
> >> +++ b/include/drm/drm_plane_helper.h
> >> @@ -41,5 +41,7 @@ int drm_plane_helper_update_primary(struct drm_plane *plane, struct drm_crtc *cr
> >>   int drm_plane_helper_disable_primary(struct drm_plane *plane,
> >>   				     struct drm_modeset_acquire_ctx *ctx);
> >>   void drm_plane_helper_destroy(struct drm_plane *plane);
> >> +int drm_plane_helper_atomic_check(struct drm_plane *plane,
> >> +				  struct drm_atomic_state *new_state);
> >>   
> >>   #endif
> >> -- 
> >> 2.37.1
> > 
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Ivo Totev




-- 
Ville Syrjälä
Intel