Re: [PATCH v6 5/6] drm/fence: add fence timeline to drm_crtc

[Brian Starkey]

On Fri, Oct 28, 2016 at 09:42:12AM +0200, Daniel Vetter wrote:
> On Thu, Oct 27, 2016 at 05:37:10PM -0200, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
> >
> > Create one timeline context for each CRTC to be able to handle out-fences
> > and signal them. It adds a few members to struct drm_crtc: fence_context,
> > where we store the context we get from fence_context_alloc(), the
> > fence seqno and the fence lock, that we pass in fence_init() to be
> > used by the fence.
> >
> > v2: Comment by Daniel Stone:
> > 	- add BUG_ON() to fence_to_crtc() macro
> >
> > v3: Comment by Ville Syrjälä
> > 	- Use more meaningful name as crtc timeline name
> >
> > v4: Comments by Brian Starkey
> > 	- Use even more meaninful name for the crtc timeline
> > 	- add doc for timeline_name
> >     Comment by Daniel Vetter
> > 	- use in-line style for comments
> >
> >     - rebase after fence -> dma_fence rename
> >
> > Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/drm_crtc.c | 31 +++++++++++++++++++++++++++++++
> >  include/drm/drm_crtc.h     | 39 +++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 70 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> > index 7878bfd..e2a06c8 100644
> > --- a/drivers/gpu/drm/drm_crtc.c
> > +++ b/drivers/gpu/drm/drm_crtc.c
> > @@ -165,6 +165,32 @@ static void drm_crtc_crc_fini(struct drm_crtc *crtc)
> >  #endif
> >  }
> >
> > +static const char *drm_crtc_fence_get_driver_name(struct dma_fence *fence)
> > +{
> > +	struct drm_crtc *crtc = fence_to_crtc(fence);
> > +
> > +	return crtc->dev->driver->name;
> > +}
> > +
> > +static const char *drm_crtc_fence_get_timeline_name(struct dma_fence *fence)
> > +{
> > +	struct drm_crtc *crtc = fence_to_crtc(fence);
> > +
> > +	return crtc->timeline_name;
> > +}
> > +
> > +static bool drm_crtc_fence_enable_signaling(struct dma_fence *fence)
> > +{
> > +	return true;
> > +}
> > +
> > +const struct dma_fence_ops drm_crtc_fence_ops = {
> > +	.get_driver_name = drm_crtc_fence_get_driver_name,
> > +	.get_timeline_name = drm_crtc_fence_get_timeline_name,
> > +	.enable_signaling = drm_crtc_fence_enable_signaling,
> > +	.wait = dma_fence_default_wait,
> > +};
> > +
> >  /**
> >   * drm_crtc_init_with_planes - Initialise a new CRTC object with
> >   *    specified primary and cursor planes.
> > @@ -222,6 +248,11 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
> >  		return -ENOMEM;
> >  	}
> >
> > +	crtc->fence_context = dma_fence_context_alloc(1);
> > +	spin_lock_init(&crtc->fence_lock);
> > +	snprintf(crtc->timeline_name, sizeof(crtc->timeline_name),
> > +		 "CRTC:%d-%s", crtc->base.id, crtc->name);
> > +
> >  	crtc->base.properties = &crtc->properties;
> >
> >  	list_add_tail(&crtc->head, &config->crtc_list);
> > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> > index 719b6a8..278dbdd 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>
> > @@ -726,8 +728,45 @@ 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];
> >  };
> >
> > +extern const struct dma_fence_ops drm_crtc_fence_ops;
> > +
>
> Kerneldoc please. With that addressed:
>
> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>

For my connector fences I exported a function to get the fence, then
you can keep the ops and fence_to_crtc private to drm_crtc.c. In that
case I think you can drop the BUG_ON.

Either way, lgtm.

Reviewed-by: Brian Starkey <brian.starkey@xxxxxxx>

> > +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);
> > +}
> > +
> >  /**
> >   * struct drm_mode_set - new values for a CRTC config change
> >   * @fb: framebuffer to use for new config
> > --
> > 2.5.5
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch