Re: [PATCH 03/11] drm/i915: Kill off intel_crtc->atomic.wait_vblank.

[Daniel Vetter <daniel@ffwll.ch>]

On Thu, Oct 22, 2015 at 01:56:28PM +0200, Maarten Lankhorst wrote:
> By handling this after the atomic helper waits for vblanks there will
> be one less wait for vblank in the atomic path.
> 
> Also get rid of the double wait_for_vblank on broadwell, looks like
> it's a bug doing the vblank wait twice.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

Problem is that the next plane update should be possible right after this
one happens, which is the potentially racing with the post_plane_update
code. What's your plan to prevent this?
-Daniel

> ---
>  drivers/gpu/drm/i915/intel_display.c | 28 +++-------------------------
>  drivers/gpu/drm/i915/intel_drv.h     |  1 -
>  2 files changed, 3 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 051a1e2b1c55..b8e1a5471bed 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4672,14 +4672,6 @@ intel_post_enable_primary(struct drm_crtc *crtc)
>  	int pipe = intel_crtc->pipe;
>  
>  	/*
> -	 * BDW signals flip done immediately if the plane
> -	 * is disabled, even if the plane enable is already
> -	 * armed to occur at the next vblank :(
> -	 */
> -	if (IS_BROADWELL(dev))
> -		intel_wait_for_vblank(dev, pipe);
> -
> -	/*
>  	 * FIXME IPS should be fine as long as one plane is
>  	 * enabled, but in practice it seems to have problems
>  	 * when going from primary only to sprite only and vice
> @@ -4760,9 +4752,6 @@ static void intel_post_plane_update(struct intel_crtc *crtc)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct drm_plane *plane;
>  
> -	if (atomic->wait_vblank)
> -		intel_wait_for_vblank(dev, crtc->pipe);
> -
>  	intel_frontbuffer_flip(dev, atomic->fb_bits);
>  
>  	if (atomic->disable_cxsr)
> @@ -11661,15 +11650,12 @@ int intel_plane_atomic_calc_changes(struct drm_crtc_state *crtc_state,
>  		if (plane->type != DRM_PLANE_TYPE_CURSOR) {
>  			intel_crtc->atomic.disable_cxsr = true;
>  			/* to potentially re-enable cxsr */
> -			intel_crtc->atomic.wait_vblank = true;
>  			intel_crtc->atomic.update_wm_post = true;
>  		}
>  	} else if (turn_off) {
>  		intel_crtc->atomic.update_wm_post = true;
>  		/* must disable cxsr around plane enable/disable */
>  		if (plane->type != DRM_PLANE_TYPE_CURSOR) {
> -			if (is_crtc_enabled)
> -				intel_crtc->atomic.wait_vblank = true;
>  			intel_crtc->atomic.disable_cxsr = true;
>  		}
>  	} else if (intel_wm_need_update(plane, plane_state)) {
> @@ -11716,21 +11702,12 @@ int intel_plane_atomic_calc_changes(struct drm_crtc_state *crtc_state,
>  		    plane_state->rotation != BIT(DRM_ROTATE_0))
>  			intel_crtc->atomic.disable_fbc = true;
>  
> -		/*
> -		 * BDW signals flip done immediately if the plane
> -		 * is disabled, even if the plane enable is already
> -		 * armed to occur at the next vblank :(
> -		 */
> -		if (turn_on && IS_BROADWELL(dev))
> -			intel_crtc->atomic.wait_vblank = true;
> -
>  		intel_crtc->atomic.update_fbc |= visible || mode_changed;
>  		break;
>  	case DRM_PLANE_TYPE_CURSOR:
>  		break;
>  	case DRM_PLANE_TYPE_OVERLAY:
>  		if (turn_off && !mode_changed) {
> -			intel_crtc->atomic.wait_vblank = true;
>  			intel_crtc->atomic.update_sprite_watermarks |=
>  				1 << i;
>  		}
> @@ -13271,14 +13248,15 @@ static int intel_atomic_commit(struct drm_device *dev,
>  
>  		if (put_domains)
>  			modeset_put_power_domains(dev_priv, put_domains);
> -
> -		intel_post_plane_update(intel_crtc);
>  	}
>  
>  	/* FIXME: add subpixel order */
>  
>  	drm_atomic_helper_wait_for_vblanks(dev, state);
>  
> +	for_each_crtc_in_state(state, crtc, crtc_state, i)
> +		intel_post_plane_update(to_intel_crtc(crtc));
> +
>  	mutex_lock(&dev->struct_mutex);
>  	drm_atomic_helper_cleanup_planes(dev, state);
>  	mutex_unlock(&dev->struct_mutex);
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 54a2c0da2ece..4b6bb1adfddd 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -522,7 +522,6 @@ struct intel_crtc_atomic_commit {
>  
>  	/* Sleepable operations to perform after commit */
>  	unsigned fb_bits;
> -	bool wait_vblank;
>  	bool update_fbc;
>  	bool post_enable_primary;
>  	unsigned update_sprite_watermarks;
> -- 
> 2.1.0
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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