Re: [RFC PATCH 03/17] drm/exynos: dsi: Use the drm_panel_bridge API

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 04.07.2021 11:02, Jagan Teki wrote:
> Use drm_panel_bridge to replace manual panel and
> bridge_chain handling code.
>
> This makes the driver simpler to allow all components
> in the display pipeline to be treated as bridges by
> cleaning the way to generic connector handling.
>
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>

This breaks Exysos DSI driver operation (Trats board worked fine with 
only patches 1-2):

[    2.540066] exynos4-fb 11c00000.fimd: Adding to iommu group 0
[    2.554733] OF: graph: no port node found in /soc/fimd@11c00000
[    2.602819] [drm] Exynos DRM: using 11c00000.fimd device for DMA 
mapping operations
[    2.609649] exynos-drm exynos-drm: bound 11c00000.fimd (ops 
fimd_component_ops)
[    2.632558] exynos-drm exynos-drm: failed to bind 11c80000.dsi (ops 
exynos_dsi_component_ops): -22
[    2.642263] exynos-drm exynos-drm: master bind failed: -22
[    2.651017] exynos-drm: probe of exynos-drm failed with error -22

> ---
>   drivers/gpu/drm/exynos/exynos_drm_dsi.c | 167 ++++--------------------
>   1 file changed, 23 insertions(+), 144 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index d7d60aee465b..24f0b082ac6d 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -254,9 +254,6 @@ struct exynos_dsi_driver_data {
>   struct exynos_dsi {
>   	struct drm_encoder encoder;
>   	struct mipi_dsi_host dsi_host;
> -	struct drm_connector connector;
> -	struct drm_panel *panel;
> -	struct list_head bridge_chain;
>   	struct drm_bridge bridge;
>   	struct drm_bridge *out_bridge;
>   	struct drm_device *drm;
> @@ -287,7 +284,6 @@ struct exynos_dsi {
>   };
>   
>   #define host_to_dsi(host) container_of(host, struct exynos_dsi, dsi_host)
> -#define connector_to_dsi(c) container_of(c, struct exynos_dsi, connector)
>   
>   static inline struct exynos_dsi *bridge_to_dsi(struct drm_bridge *b)
>   {
> @@ -1379,7 +1375,6 @@ static void exynos_dsi_unregister_te_irq(struct exynos_dsi *dsi)
>   static void exynos_dsi_bridge_enable(struct drm_bridge *bridge)
>   {
>   	struct exynos_dsi *dsi = bridge_to_dsi(bridge);
> -	struct drm_bridge *iter;
>   	int ret;
>   
>   	if (dsi->state & DSIM_STATE_ENABLED)
> @@ -1393,134 +1388,51 @@ static void exynos_dsi_bridge_enable(struct drm_bridge *bridge)
>   
>   	dsi->state |= DSIM_STATE_ENABLED;
>   
> -	if (dsi->panel) {
> -		ret = drm_panel_prepare(dsi->panel);
> -		if (ret < 0)
> -			goto err_put_sync;
> -	} else {
> -		list_for_each_entry_reverse(iter, &dsi->bridge_chain,
> -					    chain_node) {
> -			if (iter->funcs->pre_enable)
> -				iter->funcs->pre_enable(iter);
> -		}
> -	}
> -
>   	exynos_dsi_set_display_mode(dsi);
>   	exynos_dsi_set_display_enable(dsi, true);
>   
> -	if (dsi->panel) {
> -		ret = drm_panel_enable(dsi->panel);
> -		if (ret < 0)
> -			goto err_display_disable;
> -	} else {
> -		list_for_each_entry(iter, &dsi->bridge_chain, chain_node) {
> -			if (iter->funcs->enable)
> -				iter->funcs->enable(iter);
> -		}
> -	}
> -
>   	dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
>   	return;
> -
> -err_display_disable:
> -	exynos_dsi_set_display_enable(dsi, false);
> -	drm_panel_unprepare(dsi->panel);
> -
> -err_put_sync:
> -	dsi->state &= ~DSIM_STATE_ENABLED;
> -	pm_runtime_put(dsi->dev);
>   }
>   
>   static void exynos_dsi_bridge_disable(struct drm_bridge *bridge)
>   {
>   	struct exynos_dsi *dsi = bridge_to_dsi(bridge);
> -	struct drm_bridge *iter;
>   
>   	if (!(dsi->state & DSIM_STATE_ENABLED))
>   		return;
>   
>   	dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE;
>   
> -	drm_panel_disable(dsi->panel);
> -
> -	list_for_each_entry_reverse(iter, &dsi->bridge_chain, chain_node) {
> -		if (iter->funcs->disable)
> -			iter->funcs->disable(iter);
> -	}
> -
>   	exynos_dsi_set_display_enable(dsi, false);
> -	drm_panel_unprepare(dsi->panel);
> -
> -	list_for_each_entry(iter, &dsi->bridge_chain, chain_node) {
> -		if (iter->funcs->post_disable)
> -			iter->funcs->post_disable(iter);
> -	}
>   
>   	dsi->state &= ~DSIM_STATE_ENABLED;
>   	pm_runtime_put_sync(dsi->dev);
>   }
>   
> -static enum drm_connector_status
> -exynos_dsi_detect(struct drm_connector *connector, bool force)
> -{
> -	return connector->status;
> -}
> -
> -static void exynos_dsi_connector_destroy(struct drm_connector *connector)
> +static int exynos_dsi_panel_or_bridge(struct exynos_dsi *dsi,
> +				      struct device_node *node)
>   {
> -	drm_connector_unregister(connector);
> -	drm_connector_cleanup(connector);
> -	connector->dev = NULL;
> -}
> -
> -static const struct drm_connector_funcs exynos_dsi_connector_funcs = {
> -	.detect = exynos_dsi_detect,
> -	.fill_modes = drm_helper_probe_single_connector_modes,
> -	.destroy = exynos_dsi_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 int exynos_dsi_get_modes(struct drm_connector *connector)
> -{
> -	struct exynos_dsi *dsi = connector_to_dsi(connector);
> -
> -	if (dsi->panel)
> -		return drm_panel_get_modes(dsi->panel, connector);
> -
> -	return 0;
> -}
> +	struct drm_bridge *panel_bridge;
> +	struct drm_panel *panel;
>   
> -static const struct drm_connector_helper_funcs exynos_dsi_connector_helper_funcs = {
> -	.get_modes = exynos_dsi_get_modes,
> -};
> +	panel_bridge = of_drm_find_bridge(node);
> +	if (!panel_bridge) {
> +		panel = of_drm_find_panel(node);
> +		if (!IS_ERR(panel)) {
> +			panel_bridge = drm_panel_bridge_add(panel);
> +			if (IS_ERR(panel_bridge))
> +				return PTR_ERR(panel_bridge);
> +		}
> +	}
>   
> -static int exynos_dsi_create_connector(struct exynos_dsi *dsi,
> -				       struct drm_device *drm)
> -{
> -	struct drm_encoder *encoder = &dsi->encoder;
> -	struct drm_connector *connector = &dsi->connector;
> -	int ret;
> +	of_node_put(node);
>   
> -	connector->polled = DRM_CONNECTOR_POLL_HPD;
> +	dsi->out_bridge = panel_bridge;
>   
> -	ret = drm_connector_init(drm, connector, &exynos_dsi_connector_funcs,
> -				 DRM_MODE_CONNECTOR_DSI);
> -	if (ret) {
> -		DRM_DEV_ERROR(dsi->dev,
> -			      "Failed to initialize connector with drm\n");
> -		return ret;
> -	}
> +	if (!dsi->out_bridge)
> +		return -EPROBE_DEFER;
>   
> -	connector->status = connector_status_disconnected;
> -	drm_connector_helper_add(connector, &exynos_dsi_connector_helper_funcs);
> -	drm_connector_attach_encoder(connector, encoder);
> -	if (!drm->registered)
> -		return 0;
> -
> -	connector->funcs->reset(connector);
> -	drm_connector_register(connector);
>   	return 0;
>   }
>   
> @@ -1531,7 +1443,8 @@ static int exynos_dsi_bridge_attach(struct drm_bridge *bridge,
>   
>   	dsi->drm = bridge->dev;
>   
> -	return 0;
> +	return drm_bridge_attach(bridge->encoder, dsi->out_bridge, bridge,
> +				 flags);
>   }
>   
>   static const struct drm_bridge_funcs exynos_dsi_bridge_funcs = {
> @@ -1546,32 +1459,12 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
>   				  struct mipi_dsi_device *device)
>   {
>   	struct exynos_dsi *dsi = host_to_dsi(host);
> -	struct drm_encoder *encoder = &dsi->encoder;
>   	struct drm_device *drm = dsi->drm;
> -	struct drm_bridge *out_bridge;
> -
> -	out_bridge  = of_drm_find_bridge(device->dev.of_node);
> -	if (out_bridge) {
> -		drm_bridge_attach(encoder, out_bridge, NULL, 0);
> -		dsi->out_bridge = out_bridge;
> -		list_splice_init(&encoder->bridge_chain, &dsi->bridge_chain);
> -	} else {
> -		int ret = exynos_dsi_create_connector(dsi, drm);
> -
> -		if (ret) {
> -			DRM_DEV_ERROR(dsi->dev,
> -				      "failed to create connector ret = %d\n",
> -				      ret);
> -			drm_encoder_cleanup(encoder);
> -			return ret;
> -		}
> +	int ret;
>   
> -		dsi->panel = of_drm_find_panel(device->dev.of_node);
> -		if (IS_ERR(dsi->panel))
> -			dsi->panel = NULL;
> -		else
> -			dsi->connector.status = connector_status_connected;
> -	}
> +	ret = exynos_dsi_panel_or_bridge(dsi, device->dev.of_node);
> +	if (ret)
> +		return ret;
>   
>   	/*
>   	 * This is a temporary solution and should be made by more generic way.
> @@ -1607,19 +1500,6 @@ static int exynos_dsi_host_detach(struct mipi_dsi_host *host,
>   	struct exynos_dsi *dsi = host_to_dsi(host);
>   	struct drm_device *drm = dsi->drm;
>   
> -	if (dsi->panel) {
> -		mutex_lock(&drm->mode_config.mutex);
> -		exynos_dsi_bridge_disable(&dsi->bridge);
> -		dsi->panel = NULL;
> -		dsi->connector.status = connector_status_disconnected;
> -		mutex_unlock(&drm->mode_config.mutex);
> -	} else {
> -		if (dsi->out_bridge->funcs->detach)
> -			dsi->out_bridge->funcs->detach(dsi->out_bridge);
> -		dsi->out_bridge = NULL;
> -		INIT_LIST_HEAD(&dsi->bridge_chain);
> -	}
> -
>   	if (drm->mode_config.poll_enabled)
>   		drm_kms_helper_hotplug_event(drm);
>   
> @@ -1770,7 +1650,6 @@ static int exynos_dsi_probe(struct platform_device *pdev)
>   	init_completion(&dsi->completed);
>   	spin_lock_init(&dsi->transfer_lock);
>   	INIT_LIST_HEAD(&dsi->transfer_list);
> -	INIT_LIST_HEAD(&dsi->bridge_chain);
>   
>   	dsi->dsi_host.ops = &exynos_dsi_ops;
>   	dsi->dsi_host.dev = dev;

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland