Re: [PATCH] drm/i915: Use atomic page flip for intel again.

From: Daniel Vetter <daniel@ffwll.ch>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	intel-gfx@lists.freedesktop.org,
	Rafael Ristovski <rafael.ristovski@gmail.com>,
	Steven Newbury <steve@snewbury.org.uk>
Subject: Re: [PATCH] drm/i915: Use atomic page flip for intel again.
Date: Tue, 27 Dec 2016 15:48:19 +0100	[thread overview]
Message-ID: <20161227144819.GD31952@dvetter-linux.ger.corp.intel.com> (raw)
In-Reply-To: <1482402803-12557-1-git-send-email-maarten.lankhorst@linux.intel.com>

On Thu, Dec 22, 2016 at 11:33:23AM +0100, Maarten Lankhorst wrote:
> This reverts commit 527b6abe5fd2d2
> (Revert "drm/i915: Use atomic commits for legacy page_flips")
> 
> and reapplies commit ee042aa40b66d1.
> ("drm/i915: Use atomic commits for legacy page_flips")
> 
> The reason for the revert was because legacy cursor updates were
> forced to wait for pending page flips and rendering after they
> were converted to atomic.
> 
> Commit f79f26921ee12c6f
> (drm/i915: Add a cursor hack to allow converting legacy page flip to atomic, v3)
> adds a fastpath to cursor updates, which fixes the stuttering issues.
> With these changes I feel confident enough to re-enable cursor updates.
> 
> Legacy cursor update won't block in the following cases:
> - Moving cursor
> - Changing cursor fb
> 
> The legacy cursor update will still block in the following cases:
> - Showing/hiding cursor.
> - Cursor size or scaling changes.
> - cursor update while cursor is invisible (could be fixed, if it turns out to be important).
> - Cursor tiling changes (Not sure we support tiled cursors.)
> - Last update was a modeset.
> 
> Cc: Steven Newbury <steve@snewbury.org.uk>
> Cc: Rafael Ristovski <rafael.ristovski@gmail.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Tested-by: Rafael Ristovski <rafael.ristovski@gmail.com>
> Testcase: igt/kms_cursor_legacy
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

I'm going to regret this again ;-)

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index ef5dde5ab1cf..27e77ca714a5 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -12152,6 +12152,7 @@ void intel_check_page_flip(struct drm_i915_private *dev_priv, int pipe)
>  	spin_unlock(&dev->event_lock);
>  }
>  
> +__maybe_unused
>  static int intel_crtc_page_flip(struct drm_crtc *crtc,
>  				struct drm_framebuffer *fb,
>  				struct drm_pending_vblank_event *event,
> @@ -14771,7 +14772,7 @@ static const struct drm_crtc_funcs intel_crtc_funcs = {
>  	.set_config = drm_atomic_helper_set_config,
>  	.set_property = drm_atomic_helper_crtc_set_property,
>  	.destroy = intel_crtc_destroy,
> -	.page_flip = intel_crtc_page_flip,
> +	.page_flip = drm_atomic_helper_page_flip,
>  	.atomic_duplicate_state = intel_crtc_duplicate_state,
>  	.atomic_destroy_state = intel_crtc_destroy_state,
>  };
> -- 
> 2.7.4
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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