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Date:   Fri, 12 Apr 2019 16:24:24 +0100
From:   Liviu Dudau <Liviu.Dudau@arm.com>
To:     Ben Davis <Ben.Davis@arm.com>
Cc:     "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        nd <nd@arm.com>, Brian Starkey <Brian.Starkey@arm.com>,
        "airlied@linux.ie" <airlied@linux.ie>,
        "daniel@ffwll.ch" <daniel@ffwll.ch>,
        "maarten.lankhorst@linux.intel.com" 
        <maarten.lankhorst@linux.intel.com>,
        "maxime.ripard@bootlin.com" <maxime.ripard@bootlin.com>,
        "sean@poorly.run" <sean@poorly.run>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] drm: Add writeback_w,h properties
Message-ID: <20190412152424.GM15144@e110455-lin.cambridge.arm.com>
References: <1555078094-6587-1-git-send-email-ben.davis@arm.com>
 <1555078094-6587-2-git-send-email-ben.davis@arm.com>
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Hi Ben,

On Fri, Apr 12, 2019 at 03:08:28PM +0100, Ben Davis wrote:
> Add new properties to specify width and height for writeback.
> 
> Signed-off-by: Ben Davis <ben.davis@arm.com>
> ---
>  drivers/gpu/drm/drm_atomic_uapi.c |  8 ++++++++
>  drivers/gpu/drm/drm_writeback.c   | 28 ++++++++++++++++++++++++++++
>  include/drm/drm_connector.h       |  4 ++++
>  include/drm/drm_mode_config.h     | 10 ++++++++++
>  4 files changed, 50 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index d520a04..1f68dce 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -765,6 +765,10 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector,
>  			return -EINVAL;
>  		}
>  		state->content_protection = val;
> +	} else if (property == config->prop_writeback_w) {
> +		state->writeback_w = val;
> +	} else if (property == config->prop_writeback_h) {
> +		state->writeback_h = val;
>  	} else if (property == config->writeback_fb_id_property) {
>  		struct drm_framebuffer *fb = drm_framebuffer_lookup(dev, NULL, val);
>  		int ret = drm_atomic_set_writeback_fb_for_connector(state, fb);
> @@ -837,6 +841,10 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
>  		*val = state->scaling_mode;
>  	} else if (property == connector->content_protection_property) {
>  		*val = state->content_protection;
> +	} else if (property == config->prop_writeback_w) {
> +		*val = state->writeback_w;
> +	} else if (property == config->prop_writeback_h) {
> +		*val = state->writeback_h;
>  	} else if (property == config->writeback_fb_id_property) {
>  		/* Writeback framebuffer is one-shot, write and forget */
>  		*val = 0;
> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> index c20e6fe..3d0453e 100644
> --- a/drivers/gpu/drm/drm_writeback.c
> +++ b/drivers/gpu/drm/drm_writeback.c
> @@ -74,6 +74,12 @@
>   *	applications making use of writeback connectors *always* retrieve an
>   *	out-fence for the commit and use it appropriately.
>   *	From userspace, this property will always read as zero.
> + *
> + *  "WRITEBACK_W":
> + *	The width of the writeback buffer to write back. 0 acts as default.

To the "0 acts as default" I would add: "(i.e. its not set by userspace)".
I think it is worth explaining in more detail that 0 is default if no
value is set from userspace and that it also means no scaling.

Best regards,
Liviu

> + *
> + *  "WRITEBACK_H":
> + *	The height of the writeback buffer to write back. 0 acts as default.
>   */
>  
>  #define fence_to_wb_connector(x) container_of(x->lock, \
> @@ -141,6 +147,22 @@ static int create_writeback_properties(struct drm_device *dev)
>  		dev->mode_config.writeback_out_fence_ptr_property = prop;
>  	}
>  
> +	if (!dev->mode_config.prop_writeback_w) {
> +		prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC,
> +						 "WRITEBACK_W", 1, UINT_MAX);
> +		if (!prop)
> +			return -ENOMEM;
> +		dev->mode_config.prop_writeback_w = prop;
> +	}
> +
> +	if (!dev->mode_config.prop_writeback_h) {
> +		prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC,
> +						 "WRITEBACK_H", 1, UINT_MAX);
> +		if (!prop)
> +			return -ENOMEM;
> +		dev->mode_config.prop_writeback_h = prop;
> +	}
> +
>  	return 0;
>  }
>  
> @@ -225,6 +247,12 @@ int drm_writeback_connector_init(struct drm_device *dev,
>  	drm_object_attach_property(&connector->base,
>  				   config->writeback_pixel_formats_property,
>  				   blob->base.id);
> +
> +	drm_object_attach_property(&connector->base,
> +				   config->prop_writeback_w, 0);
> +	drm_object_attach_property(&connector->base,
> +				   config->prop_writeback_h, 0);
> +
>  	wb_connector->pixel_formats_blob_ptr = blob;
>  
>  	return 0;
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 8fe22ab..51c4cb2 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -515,6 +515,10 @@ struct drm_connector_state {
>  	 */
>  	struct drm_writeback_job *writeback_job;
>  
> +	/** @writeback_w: width of plane to write to wb buffer */
> +	/** @writeback_h: height of plane to write to wb buffer */
> +	uint32_t writeback_w, writeback_h;
> +
>  	/**
>  	 * @max_requested_bpc: Connector property to limit the maximum bit
>  	 * depth of the pixels.
> diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> index 7f60e8e..a0c2133 100644
> --- a/include/drm/drm_mode_config.h
> +++ b/include/drm/drm_mode_config.h
> @@ -622,6 +622,16 @@ struct drm_mode_config {
>  	 */
>  	struct drm_property *prop_crtc_h;
>  	/**
> +	 * @prop_writeback_w: Writeback connector property for the plane
> +	 * destination position in the writeback buffer.
> +	 */
> +	struct drm_property *prop_writeback_w;
> +	/**
> +	 * @prop_writeback_h: Writeback connector property for the plane
> +	 * destination position in the writeback buffer.
> +	 */
> +	struct drm_property *prop_writeback_h;
> +	/**
>  	 * @prop_fb_id: Default atomic plane property to specify the
>  	 * &drm_framebuffer.
>  	 */
> -- 
> 2.7.4
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯