linux-kernel - Re: [PATCH v11 2/3] drm/fence: add fence timeline to drm

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Message-ID: <20161115085233.mykggy5sn3kcjeen@phenom.ffwll.local>
Date:   Tue, 15 Nov 2016 09:52:33 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gustavo Padovan <gustavo@...ovan.org>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        dri-devel@...ts.freedesktop.org, marcheu@...gle.com,
        Daniel Stone <daniels@...labora.com>, seanpaul@...gle.com,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        linux-kernel@...r.kernel.org, laurent.pinchart@...asonboard.com,
        Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
        John Harrison <John.C.Harrison@...el.com>, m.chehab@...sung.com
Subject: Re: [PATCH v11 2/3] drm/fence: add fence timeline to drm_crtc

On Tue, Nov 15, 2016 at 05:42:35PM +0900, Gustavo Padovan wrote:
> 2016-11-15 Chris Wilson <chris@...is-wilson.co.uk>:
> 
> > On Tue, Nov 15, 2016 at 10:57:35AM +0900, Gustavo Padovan wrote:
> > > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> > > index 11780a9..0870de1 100644
> > > --- a/include/drm/drm_crtc.h
> > > +++ b/include/drm/drm_crtc.h
> > > @@ -32,6 +32,8 @@
> > >  #include <linux/fb.h>
> > >  #include <linux/hdmi.h>
> > >  #include <linux/media-bus-format.h>
> > > +#include <linux/srcu.h>
> > > +#include <linux/dma-fence.h>
> > >  #include <uapi/drm/drm_mode.h>
> > >  #include <uapi/drm/drm_fourcc.h>
> > >  #include <drm/drm_modeset_lock.h>
> > > @@ -739,9 +741,52 @@ struct drm_crtc {
> > >  	 */
> > >  	struct drm_crtc_crc crc;
> > >  #endif
> > > +
> > > +	/**
> > > +	 * @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 CRTC's timeline.
> > > +	 */
> > > +	unsigned long fence_seqno;
> > > +
> > > +	/**
> > > +	 * @timeline_name:
> > > +	 *
> > > +	 * The name of the CRTC's fence timeline.
> > > +	 */
> > > +	char timeline_name[32];
> > >  };
> > >  
> > >  /**
> > > + * dma_crtc_fence_ops - fence ops for the drm_crtc timeline
> > > + *
> > > + * It contains the dma_fence_ops that should be called by the dma_fence
> > > + * code. CRTC core should use this ops when initializing fences.
> > > + */
> > > +extern const struct dma_fence_ops drm_crtc_fence_ops;
> > > +
> > > +static inline struct drm_crtc *fence_to_crtc(struct dma_fence *fence)
> > > +{
> > > +	BUG_ON(fence->ops != &drm_crtc_fence_ops);
> > > +	return container_of(fence->lock, struct drm_crtc, fence_lock);
> > > +}
> > 
> > If you are planning to export this for use by drivers, you are missing
> > the EXPORT_SYMBOL(drm_crtc_fence_ops).
> 
> Drivers should not be using this, at least for now.

Then please put it into drm_crtc_internal.h. We should only allow drivers
to use functions they're supposed to be using, and hide everything else.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch