Date:   Fri, 12 May 2017 10:04:26 +0200
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org,
        Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        CK Hu <ck.hu@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Yannick Fertre <yannick.fertre@...com>,
        Philippe Cornu <philippe.cornu@...com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/7] drm/vc4: Switch DPI to using the panel-bridge
 helper.

On Thu, 11 May 2017 11:31:24 -0700
Eric Anholt <eric@...olt.net> wrote:

> Another 100 lines of boilerplate gone, while allowing for bridges to
> be connected in the display chain.
> 
> Signed-off-by: Eric Anholt <eric@...olt.net>

Reviewed-by: Boris Brezillon <boris.brezillon@...e-electrons.com>

> ---
>  drivers/gpu/drm/vc4/vc4_dpi.c | 164 ++++++++----------------------------------
>  1 file changed, 30 insertions(+), 134 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c
> index c6d703903fd9..98532e2cd2b7 100644
> --- a/drivers/gpu/drm/vc4/vc4_dpi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dpi.c
> @@ -23,8 +23,10 @@
>   */
>  
>  #include "drm_atomic_helper.h"
> +#include "drm_bridge.h"
>  #include "drm_crtc_helper.h"
>  #include "drm_edid.h"
> +#include "drm_of.h"
>  #include "drm_panel.h"
>  #include "linux/clk.h"
>  #include "linux/component.h"
> @@ -95,7 +97,8 @@ struct vc4_dpi {
>  
>  	struct drm_encoder *encoder;
>  	struct drm_connector *connector;
> -	struct drm_panel *panel;
> +	struct drm_bridge *bridge;
> +	bool is_panel_bridge;
>  
>  	void __iomem *regs;
>  
> @@ -118,24 +121,6 @@ to_vc4_dpi_encoder(struct drm_encoder *encoder)
>  	return container_of(encoder, struct vc4_dpi_encoder, base.base);
>  }
>  
> -/* VC4 DPI connector KMS struct */
> -struct vc4_dpi_connector {
> -	struct drm_connector base;
> -	struct vc4_dpi *dpi;
> -
> -	/* Since the connector is attached to just the one encoder,
> -	 * this is the reference to it so we can do the best_encoder()
> -	 * hook.
> -	 */
> -	struct drm_encoder *encoder;
> -};
> -
> -static inline struct vc4_dpi_connector *
> -to_vc4_dpi_connector(struct drm_connector *connector)
> -{
> -	return container_of(connector, struct vc4_dpi_connector, base);
> -}
> -
>  #define DPI_REG(reg) { reg, #reg }
>  static const struct {
>  	u32 reg;
> @@ -167,80 +152,6 @@ int vc4_dpi_debugfs_regs(struct seq_file *m, void *unused)
>  }
>  #endif
>  
> -static enum drm_connector_status
> -vc4_dpi_connector_detect(struct drm_connector *connector, bool force)
> -{
> -	struct vc4_dpi_connector *vc4_connector =
> -		to_vc4_dpi_connector(connector);
> -	struct vc4_dpi *dpi = vc4_connector->dpi;
> -
> -	if (dpi->panel)
> -		return connector_status_connected;
> -	else
> -		return connector_status_disconnected;
> -}
> -
> -static void vc4_dpi_connector_destroy(struct drm_connector *connector)
> -{
> -	drm_connector_unregister(connector);
> -	drm_connector_cleanup(connector);
> -}
> -
> -static int vc4_dpi_connector_get_modes(struct drm_connector *connector)
> -{
> -	struct vc4_dpi_connector *vc4_connector =
> -		to_vc4_dpi_connector(connector);
> -	struct vc4_dpi *dpi = vc4_connector->dpi;
> -
> -	if (dpi->panel)
> -		return drm_panel_get_modes(dpi->panel);
> -
> -	return 0;
> -}
> -
> -static const struct drm_connector_funcs vc4_dpi_connector_funcs = {
> -	.dpms = drm_atomic_helper_connector_dpms,
> -	.detect = vc4_dpi_connector_detect,
> -	.fill_modes = drm_helper_probe_single_connector_modes,
> -	.destroy = vc4_dpi_connector_destroy,
> -	.reset = drm_atomic_helper_connector_reset,
> -	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> -	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> -};
> -
> -static const struct drm_connector_helper_funcs vc4_dpi_connector_helper_funcs = {
> -	.get_modes = vc4_dpi_connector_get_modes,
> -};
> -
> -static struct drm_connector *vc4_dpi_connector_init(struct drm_device *dev,
> -						    struct vc4_dpi *dpi)
> -{
> -	struct drm_connector *connector = NULL;
> -	struct vc4_dpi_connector *dpi_connector;
> -
> -	dpi_connector = devm_kzalloc(dev->dev, sizeof(*dpi_connector),
> -				     GFP_KERNEL);
> -	if (!dpi_connector)
> -		return ERR_PTR(-ENOMEM);
> -
> -	connector = &dpi_connector->base;
> -
> -	dpi_connector->encoder = dpi->encoder;
> -	dpi_connector->dpi = dpi;
> -
> -	drm_connector_init(dev, connector, &vc4_dpi_connector_funcs,
> -			   DRM_MODE_CONNECTOR_DPI);
> -	drm_connector_helper_add(connector, &vc4_dpi_connector_helper_funcs);
> -
> -	connector->polled = 0;
> -	connector->interlace_allowed = 0;
> -	connector->doublescan_allowed = 0;
> -
> -	drm_mode_connector_attach_encoder(connector, dpi->encoder);
> -
> -	return connector;
> -}
> -
>  static const struct drm_encoder_funcs vc4_dpi_encoder_funcs = {
>  	.destroy = drm_encoder_cleanup,
>  };
> @@ -250,11 +161,7 @@ static void vc4_dpi_encoder_disable(struct drm_encoder *encoder)
>  	struct vc4_dpi_encoder *vc4_encoder = to_vc4_dpi_encoder(encoder);
>  	struct vc4_dpi *dpi = vc4_encoder->dpi;
>  
> -	drm_panel_disable(dpi->panel);
> -
>  	clk_disable_unprepare(dpi->pixel_clock);
> -
> -	drm_panel_unprepare(dpi->panel);
>  }
>  
>  static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
> @@ -265,12 +172,6 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
>  	u32 dpi_c = DPI_ENABLE | DPI_OUTPUT_ENABLE_MODE;
>  	int ret;
>  
> -	ret = drm_panel_prepare(dpi->panel);
> -	if (ret) {
> -		DRM_ERROR("Panel failed to prepare\n");
> -		return;
> -	}
> -
>  	if (dpi->connector->display_info.num_bus_formats) {
>  		u32 bus_format = dpi->connector->display_info.bus_formats[0];
>  
> @@ -321,13 +222,6 @@ static void vc4_dpi_encoder_enable(struct drm_encoder *encoder)
>  	ret = clk_prepare_enable(dpi->pixel_clock);
>  	if (ret)
>  		DRM_ERROR("Failed to set clock rate: %d\n", ret);
> -
> -	ret = drm_panel_enable(dpi->panel);
> -	if (ret) {
> -		DRM_ERROR("Panel failed to enable\n");
> -		drm_panel_unprepare(dpi->panel);
> -		return;
> -	}
>  }
>  
>  static bool vc4_dpi_encoder_mode_fixup(struct drm_encoder *encoder,
> @@ -351,24 +245,34 @@ static const struct of_device_id vc4_dpi_dt_match[] = {
>  	{}
>  };
>  
> -/* Walks the OF graph to find the panel node and then asks DRM to look
> - * up the panel.
> +/* Sets up the next link in the display chain, whether it's a panel or
> + * a bridge.
>   */
> -static struct drm_panel *vc4_dpi_get_panel(struct device *dev)
> +static int vc4_dpi_init_bridge(struct vc4_dpi *dpi)
>  {
> -	struct device_node *panel_node;
> -	struct device_node *np = dev->of_node;
> +	struct device *dev = &dpi->pdev->dev;
>  	struct drm_panel *panel;
> +	int ret;
>  
> -	/* don't proceed if we have an endpoint but no panel_node tied to it */
> -	panel_node = of_graph_get_remote_node(np, 0, 0);
> -	if (!panel_node)
> -		return NULL;
> +	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> +					  &panel, &dpi->bridge);
> +	if (ret) {
> +		/* If nothing was connected in the DT, that's not an
> +		 * error.
> +		 */
> +		if (ret == -ENODEV)
> +			return 0;
> +		else
> +			return ret;
> +	}
>  
> -	panel = of_drm_find_panel(panel_node);
> -	of_node_put(panel_node);
> +	if (panel) {
> +		dpi->bridge = drm_panel_bridge_add(panel,
> +						   DRM_MODE_CONNECTOR_DPI);
> +		dpi->is_panel_bridge = true;
> +	}
>  
> -	return panel;
> +	return drm_bridge_attach(dpi->encoder, dpi->bridge, NULL);
>  }
>  
>  static int vc4_dpi_bind(struct device *dev, struct device *master, void *data)
> @@ -422,20 +326,13 @@ static int vc4_dpi_bind(struct device *dev, struct device *master, void *data)
>  	if (ret)
>  		DRM_ERROR("Failed to turn on core clock: %d\n", ret);
>  
> -	dpi->panel = vc4_dpi_get_panel(dev);
> -
>  	drm_encoder_init(drm, dpi->encoder, &vc4_dpi_encoder_funcs,
>  			 DRM_MODE_ENCODER_DPI, NULL);
>  	drm_encoder_helper_add(dpi->encoder, &vc4_dpi_encoder_helper_funcs);
>  
> -	dpi->connector = vc4_dpi_connector_init(drm, dpi);
> -	if (IS_ERR(dpi->connector)) {
> -		ret = PTR_ERR(dpi->connector);
> +	ret = vc4_dpi_init_bridge(dpi);
> +	if (ret)
>  		goto err_destroy_encoder;
> -	}
> -
> -	if (dpi->panel)
> -		drm_panel_attach(dpi->panel, dpi->connector);
>  
>  	dev_set_drvdata(dev, dpi);
>  
> @@ -456,10 +353,9 @@ static void vc4_dpi_unbind(struct device *dev, struct device *master,
>  	struct vc4_dev *vc4 = to_vc4_dev(drm);
>  	struct vc4_dpi *dpi = dev_get_drvdata(dev);
>  
> -	if (dpi->panel)
> -		drm_panel_detach(dpi->panel);
> +	if (dpi->is_panel_bridge)
> +		drm_panel_bridge_remove(dpi->bridge);
>  
> -	vc4_dpi_connector_destroy(dpi->connector);
>  	drm_encoder_cleanup(dpi->encoder);
>  
>  	clk_disable_unprepare(dpi->core_clock);

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