Re: [PATCH 1/5] drm/i915: Make plane fb tracking work correctly, v2.

[Ander Conselvan De Oliveira <conselvan2@gmail.com>]

On Wed, 2015-09-23 at 13:27 +0200, Maarten Lankhorst wrote:
> atomic->disabled_planes is a hack that had to exist because
> prepare_fb was only called when a new fb was set. This messed
> up fb tracking in some circumstances like aborts from
> interruptible waits. As a result interruptible waiting in
> prepare_plane_fb was forbidden, but other errors could still
> cause frontbuffer tracking to be messed up.
> 
> Now that prepare_fb is always called, this hack is no longer
> required and prepare_fb may fail without consequences.
> 
> Changes since v1:
> - Clean up a few fb tracking warnings by changing plane->fb to
>   plane->state->fb.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 47 ++++++++++++++----------------------
>  drivers/gpu/drm/i915/intel_drv.h     |  1 -
>  2 files changed, 18 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index fc0086748b71..ac97af69be62 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4752,17 +4752,6 @@ static void intel_pre_plane_update(struct intel_crtc *crtc)
>  	struct drm_device *dev = crtc->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_crtc_atomic_commit *atomic = &crtc->atomic;
> -	struct drm_plane *p;
> -
> -	/* Track fb's for any planes being disabled */
> -	drm_for_each_plane_mask(p, dev, atomic->disabled_planes) {
> -		struct intel_plane *plane = to_intel_plane(p);
> -
> -		mutex_lock(&dev->struct_mutex);
> -		i915_gem_track_fb(intel_fb_obj(plane->base.fb), NULL,
> -				  plane->frontbuffer_bit);
> -		mutex_unlock(&dev->struct_mutex);
> -	}
>  
>  	if (atomic->wait_for_flips)
>  		intel_crtc_wait_for_pending_flips(&crtc->base);
> @@ -11561,14 +11550,6 @@ int intel_plane_atomic_calc_changes(struct drm_crtc_state *crtc_state,
>  			return ret;
>  	}
>  
> -	/*
> -	 * Disabling a plane is always okay; we just need to update
> -	 * fb tracking in a special way since cleanup_fb() won't
> -	 * get called by the plane helpers.
> -	 */
> -	if (old_plane_state->base.fb && !fb)
> -		intel_crtc->atomic.disabled_planes |= 1 << i;
> -
>  	was_visible = old_plane_state->visible;
>  	visible = to_intel_plane_state(plane_state)->visible;
>  
> @@ -13318,15 +13299,17 @@ intel_prepare_plane_fb(struct drm_plane *plane,
>  	struct drm_framebuffer *fb = new_state->fb;
>  	struct intel_plane *intel_plane = to_intel_plane(plane);
>  	struct drm_i915_gem_object *obj = intel_fb_obj(fb);
> -	struct drm_i915_gem_object *old_obj = intel_fb_obj(plane->fb);
> +	struct drm_i915_gem_object *old_obj = intel_fb_obj(plane->state->fb);
>  	int ret = 0;
>  
> -	if (!obj)
> +	if (!obj && !old_obj)
>  		return 0;
>  
>  	mutex_lock(&dev->struct_mutex);
>  
> -	if (plane->type == DRM_PLANE_TYPE_CURSOR &&
> +	if (!obj) {
> +		ret = 0;
> +	} else if (plane->type == DRM_PLANE_TYPE_CURSOR &&
>  	    INTEL_INFO(dev)->cursor_needs_physical) {
>  		int align = IS_I830(dev) ? 16 * 1024 : 256;
>  		ret = i915_gem_object_attach_phys(obj, align);
> @@ -13356,17 +13339,23 @@ intel_cleanup_plane_fb(struct drm_plane *plane,
>  		       const struct drm_plane_state *old_state)
>  {
>  	struct drm_device *dev = plane->dev;
> -	struct drm_i915_gem_object *obj = intel_fb_obj(old_state->fb);
> +	struct intel_plane *intel_plane = to_intel_plane(plane);
> +	struct drm_i915_gem_object *old_obj = intel_fb_obj(old_state->fb);
> +	struct drm_i915_gem_object *obj = intel_fb_obj(plane->state->fb);
>  
> -	if (!obj)
> +	if (!obj && !old_obj)
>  		return;
>  
> -	if (plane->type != DRM_PLANE_TYPE_CURSOR ||
> -	    !INTEL_INFO(dev)->cursor_needs_physical) {
> -		mutex_lock(&dev->struct_mutex);
> +	mutex_lock(&dev->struct_mutex);
> +	if (old_obj && (plane->type != DRM_PLANE_TYPE_CURSOR ||
> +	    !INTEL_INFO(dev)->cursor_needs_physical))
>  		intel_unpin_fb_obj(old_state->fb, old_state);
> -		mutex_unlock(&dev->struct_mutex);
> -	}
> +
> +	/* prepare_fb aborted? */
> +	if ((old_obj && (old_obj->frontbuffer_bits & intel_plane->frontbuffer_bit)) ||
> +	    (obj && !(obj->frontbuffer_bits & intel_plane->frontbuffer_bit)))
> +		i915_gem_track_fb(old_obj, obj, intel_plane->frontbuffer_bit);

I'm not a fan of this big condition. Would it make sense to add a new parameter to cleanup_fb() that
tells us if this is an abort clean up?

But in any case, that can be done later.

Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>

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