Re: [PATCH v3 2/3] v4l: vsp1: Extend VSP1 module API to allow DRM callbacks

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Cc: linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v3 2/3] v4l: vsp1: Extend VSP1 module API to allow DRM callbacks
Date: Sun, 05 Mar 2017 23:58:33 +0200	[thread overview]
Message-ID: <16730350.NvnRv331tg@avalon> (raw)
In-Reply-To: <200127cf978c8d8904e43ab2b28a225e8a786f6e.1488729419.git-series.kieran.bingham+renesas@ideasonboard.com>

Hi Kieran,

Thank you for the patch.

On Sunday 05 Mar 2017 16:00:03 Kieran Bingham wrote:
> To be able to perform page flips in DRM without flicker we need to be
> able to notify the rcar-du module when the VSP has completed its
> processing.
> 
> We must not have bidirectional dependencies on the two components to
> maintain support for loadable modules, thus we extend the API to allow
> a callback to be registered within the VSP DRM interface.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> ---
>  drivers/media/platform/vsp1/vsp1_drm.c | 17 +++++++++++++++++
>  drivers/media/platform/vsp1/vsp1_drm.h | 11 +++++++++++
>  include/media/vsp1.h                   | 13 +++++++++++++
>  3 files changed, 41 insertions(+)
> 
> diff --git a/drivers/media/platform/vsp1/vsp1_drm.c
> b/drivers/media/platform/vsp1/vsp1_drm.c index 4ee437c7ff0c..d93bf7d3a39e
> 100644
> --- a/drivers/media/platform/vsp1/vsp1_drm.c
> +++ b/drivers/media/platform/vsp1/vsp1_drm.c
> @@ -37,6 +37,14 @@ void vsp1_drm_display_start(struct vsp1_device *vsp1)
>  	vsp1_dlm_irq_display_start(vsp1->drm->pipe.output->dlm);
>  }
> 
> +static void vsp1_du_pipeline_frame_end(struct vsp1_pipeline *pipe)
> +{
> +	struct vsp1_drm *drm = to_vsp1_drm(pipe);
> +
> +	if (drm->du_complete)
> +		drm->du_complete(drm->du_private);
> +}
> +
>  /* ------------------------------------------------------------------------
>   * DU Driver API
>   */
> @@ -96,6 +104,7 @@ int vsp1_du_setup_lif(struct device *dev, const struct
> vsp1_du_lif_config *cfg) }
> 
>  		pipe->num_inputs = 0;
> +		vsp1->drm->du_complete = NULL;
> 
>  		vsp1_dlm_reset(pipe->output->dlm);
>  		vsp1_device_put(vsp1);
> @@ -200,6 +209,13 @@ int vsp1_du_setup_lif(struct device *dev, const struct
> vsp1_du_lif_config *cfg) if (ret < 0)
>  		return ret;
> 
> +	/*
> +	 * Register a callback to allow us to notify the DRM framework of 
frame

s/framework/driver/

> +	 * completion events.
> +	 */
> +	vsp1->drm->du_complete = cfg->callback;
> +	vsp1->drm->du_private = cfg->callback_data;
> +
>  	ret = media_pipeline_start(&pipe->output->entity.subdev.entity,
>  					  &pipe->pipe);
>  	if (ret < 0) {
> @@ -607,6 +623,7 @@ int vsp1_drm_init(struct vsp1_device *vsp1)
>  	pipe->lif = &vsp1->lif->entity;
>  	pipe->output = vsp1->wpf[0];
>  	pipe->output->pipe = pipe;
> +	pipe->frame_end = vsp1_du_pipeline_frame_end;
> 
>  	return 0;
>  }
> diff --git a/drivers/media/platform/vsp1/vsp1_drm.h
> b/drivers/media/platform/vsp1/vsp1_drm.h index c8d2f88fc483..3de2095cb0ce
> 100644
> --- a/drivers/media/platform/vsp1/vsp1_drm.h
> +++ b/drivers/media/platform/vsp1/vsp1_drm.h
> @@ -23,6 +23,8 @@
>   * @num_inputs: number of active pipeline inputs at the beginning of an
> update
>   * @inputs: source crop rectangle, destination compose rectangle and
> z-order
>   *	position for every input
> + * @du_complete: frame completion callback for the DU driver (optional)
> + * @du_private: data to be passed to the du_complete callback
>   */
>  struct vsp1_drm {
>  	struct vsp1_pipeline pipe;
> @@ -33,8 +35,17 @@ struct vsp1_drm {
>  		struct v4l2_rect compose;
>  		unsigned int zpos;
>  	} inputs[VSP1_MAX_RPF];
> +
> +	/* Frame syncronisation */

s/syncronisation/synchronisation/

> +	void (*du_complete)(void *);
> +	void *du_private;
>  };
> 
> +static inline struct vsp1_drm *to_vsp1_drm(struct vsp1_pipeline *pipe)
> +{
> +	return container_of(pipe, struct vsp1_drm, pipe);
> +}
> +
>  int vsp1_drm_init(struct vsp1_device *vsp1);
>  void vsp1_drm_cleanup(struct vsp1_device *vsp1);
>  int vsp1_drm_create_links(struct vsp1_device *vsp1);
> diff --git a/include/media/vsp1.h b/include/media/vsp1.h
> index bfc701f04f3f..d59d0adf560d 100644
> --- a/include/media/vsp1.h
> +++ b/include/media/vsp1.h
> @@ -20,9 +20,22 @@ struct device;
> 
>  int vsp1_du_init(struct device *dev);
> 
> +/**
> + * struct vsp1_du_lif_config - VSP LIF configuration
> + * @width: output frame width
> + * @height: output frame height
> + * @callback: frame completion callback function (optional)
> + * @callback_data: data to be passed to the frame completion callback
> + *
> + * When the optional callback is provided to the VSP1, the VSP1 must
> guarantee
> + * that one completion callback is performed after every
> vsp1_du_atomic_flush()

This paragraph should be part of the @callback documentation. I would phrase 
it as

 * @callback: frame completion callback function (optional). When a callback
 *	      is provided, the VSP driver guarantees that it will be called
 *	      once and only once for each vsp1_du_atomic_flush() call.

With this fixed,

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

If you're fine with the above changes there's no need to resubmit, I'll fix 
when applying the patch.

> + */
>  struct vsp1_du_lif_config {
>  	unsigned int width;
>  	unsigned int height;
> +
> +	void (*callback)(void *);
> +	void *callback_data;
>  };
> 
>  int vsp1_du_setup_lif(struct device *dev, const struct vsp1_du_lif_config
> *cfg);

-- 
Regards,

Laurent Pinchart