linux-kernel - Re: [PATCH v8 2/3] drm: writeback: Add out-fences for writeback connectors

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Date:   Tue, 22 May 2018 17:35:50 +0100
From:   Liviu Dudau <Liviu.Dudau@....com>
To:     Eric Anholt <eric@...olt.net>
Cc:     Gustavo Padovan <gustavo@...ovan.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        Jonathan Corbet <corbet@....net>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        David Airlie <airlied@...ux.ie>,
        Brian Starkey <brian.starkey@....com>,
        Alexandru-Cosmin Gheorghe <alexandru-cosmin.gheorghe@....com>,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Daniel Stone <daniels@...labora.com>,
        Mihail Atanassov <mihail.atanassov@....com>
Subject: Re: [PATCH v8 2/3] drm: writeback: Add out-fences for writeback
 connectors

On Mon, May 21, 2018 at 12:02:25PM -0700, Eric Anholt wrote:
> Liviu Dudau <Liviu.Dudau@....com> writes:
> 
> > From: Brian Starkey <brian.starkey@....com>
> >
> > Add the WRITEBACK_OUT_FENCE_PTR property to writeback connectors, to
> > enable userspace to get a fence which will signal once the writeback is
> > complete. It is not allowed to request an out-fence without a
> > framebuffer attached to the connector.
> >
> > A timeline is added to drm_writeback_connector for use by the writeback
> > out-fences.
> 
> 
> > diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h
> > index cf3a28676006a..6a7462c1821ad 100644
> > --- a/include/drm/drm_writeback.h
> > +++ b/include/drm/drm_writeback.h
> > @@ -49,6 +49,32 @@ struct drm_writeback_connector {
> >  	 * drm_writeback_signal_completion()
> >  	 */
> >  	struct list_head job_queue;
> > +
> > +	/**
> > +	 * @fence_context:
> > +	 *
> > +	 * timeline context used for fence operations.
> > +	 */
> > +	unsigned int fence_context;
> > +	/**
> > +	 * @fence_lock:
> > +	 *
> > +	 * spinlock to protect the fences in the fence_context.
> > +	 */
> > +	spinlock_t fence_lock;
> > +	/**
> > +	 * @fence_seqno:
> > +	 *
> > +	 * Seqno variable used as monotonic counter for the fences
> > +	 * created on the connector's timeline.
> > +	 */
> > +	unsigned long fence_seqno;
> > +	/**
> > +	 * @timeline_name:
> > +	 *
> > +	 * The name of the connector's fence timeline.
> > +	 */
> > +	char timeline_name[32];
> >  };
> >  
> >  struct drm_writeback_job {
> > @@ -59,12 +85,14 @@ struct drm_writeback_job {
> >  	 * framebuffer reference to a workqueue.
> >  	 */
> >  	struct work_struct cleanup_work;
> > +
> >  	/**
> >  	 * @list_entry:
> >  	 *
> >  	 * List item for the connector's @job_queue
> >  	 */
> >  	struct list_head list_entry;
> > +
> >  	/**
> >  	 * @fb:
> >  	 *
> 
> Move this hunk into patch 1?

I can, however this is the only change I will be making. Is it worth
respinning a new revision for it?

> 
> Other than that, the series is:
> 
> Reviewed-by: Eric Anholt <eric@...olt.net>

Many thanks for that!

> 
> It's pretty clean and makes sense to me.  I only had some questions
> about the job_queue, which seems superfluous if we aren't supporting
> firing off a new writeback while an old one is outstanding (and maybe we
> should throw an error in that case).  Still, I think this is ready to land.

I know Sean and Daniel are on holiday. Are you OK to pull this into
drm-misc? Should I ask Gustavo to do it?

Best regards,
Liviu

-- 
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