drivers/gpu/drm/drm_bridge_connector.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2019 Laurent Pinchart <[email protected]>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/slab.h>
   9
  10 #include <drm/drm_atomic_state_helper.h>
  11 #include <drm/drm_bridge.h>
  12 #include <drm/drm_bridge_connector.h>
  13 #include <drm/drm_connector.h>
  14 #include <drm/drm_device.h>
  15 #include <drm/drm_edid.h>
  16 #include <drm/drm_modeset_helper_vtables.h>
  17 #include <drm/drm_probe_helper.h>
  18
  19 /**
  20  * DOC: overview
  21  *
  22  * The DRM bridge connector helper object provides a DRM connector
  23  * implementation that wraps a chain of &struct drm_bridge. The connector
  24  * operations are fully implemented based on the operations of the bridges in
  25  * the chain, and don't require any intervention from the display controller
  26  * driver at runtime.
  27  *
  28  * To use the helper, display controller drivers create a bridge connector with
  29  * a call to drm_bridge_connector_init(). This associates the newly created
  30  * connector with the chain of bridges passed to the function and registers it
  31  * with the DRM device. At that point the connector becomes fully usable, no
  32  * further operation is needed.
  33  *
  34  * The DRM bridge connector operations are implemented based on the operations
  35  * provided by the bridges in the chain. Each connector operation is delegated
  36  * to the bridge closest to the connector (at the end of the chain) that
  37  * provides the relevant functionality.
  38  *
  39  * To make use of this helper, all bridges in the chain shall report bridge
  40  * operation flags (&drm_bridge->ops) and bridge output type
  41  * (&drm_bridge->type), as well as the DRM_BRIDGE_ATTACH_NO_CONNECTOR attach
  42  * flag (none of the bridges shall create a DRM connector directly).
  43  */
  44
  45 /**
  46  * struct drm_bridge_connector - A connector backed by a chain of bridges
  47  */
  48 struct drm_bridge_connector {
  49         /**
  50          * @base: The base DRM connector
  51          */
  52         struct drm_connector base;
  53         /**
  54          * @encoder:
  55          *
  56          * The encoder at the start of the bridges chain.
  57          */
  58         struct drm_encoder *encoder;
  59         /**
  60          * @bridge_edid:
  61          *
  62          * The last bridge in the chain (closest to the connector) that provides
  63          * EDID read support, if any (see &DRM_BRIDGE_OP_EDID).
  64          */
  65         struct drm_bridge *bridge_edid;
  66         /**
  67          * @bridge_hpd:
  68          *
  69          * The last bridge in the chain (closest to the connector) that provides
  70          * hot-plug detection notification, if any (see &DRM_BRIDGE_OP_HPD).
  71          */
  72         struct drm_bridge *bridge_hpd;
  73         /**
  74          * @bridge_detect:
  75          *
  76          * The last bridge in the chain (closest to the connector) that provides
  77          * connector detection, if any (see &DRM_BRIDGE_OP_DETECT).
  78          */
  79         struct drm_bridge *bridge_detect;
  80         /**
  81          * @bridge_modes:
  82          *
  83          * The last bridge in the chain (closest to the connector) that provides
  84          * connector modes detection, if any (see &DRM_BRIDGE_OP_MODES).
  85          */
  86         struct drm_bridge *bridge_modes;
  87 };
  88
  89 #define to_drm_bridge_connector(x) \
  90         container_of(x, struct drm_bridge_connector, base)
  91
  92 /* -----------------------------------------------------------------------------
  93  * Bridge Connector Hot-Plug Handling
  94  */
  95
  96 static void drm_bridge_connector_hpd_notify(struct drm_connector *connector,
  97                                             enum drm_connector_status status)
  98 {
  99         struct drm_bridge_connector *bridge_connector =
 100                 to_drm_bridge_connector(connector);
 101         struct drm_bridge *bridge;
 102
 103         /* Notify all bridges in the pipeline of hotplug events. */
 104         drm_for_each_bridge_in_chain(bridge_connector->encoder, bridge) {
 105                 if (bridge->funcs->hpd_notify)
 106                         bridge->funcs->hpd_notify(bridge, status);
 107         }
 108 }
 109
 110 static void drm_bridge_connector_hpd_cb(void *cb_data,
 111                                         enum drm_connector_status status)
 112 {
 113         struct drm_bridge_connector *drm_bridge_connector = cb_data;
 114         struct drm_connector *connector = &drm_bridge_connector->base;
 115         struct drm_device *dev = connector->dev;
 116         enum drm_connector_status old_status;
 117
 118         mutex_lock(&dev->mode_config.mutex);
 119         old_status = connector->status;
 120         connector->status = status;
 121         mutex_unlock(&dev->mode_config.mutex);
 122
 123         if (old_status == status)
 124                 return;
 125
 126         drm_bridge_connector_hpd_notify(connector, status);
 127
 128         drm_kms_helper_hotplug_event(dev);
 129 }
 130
 131 /**
 132  * drm_bridge_connector_enable_hpd - Enable hot-plug detection for the connector
 133  * @connector: The DRM bridge connector
 134  *
 135  * This function enables hot-plug detection for the given bridge connector.
 136  * This is typically used by display drivers in their resume handler.
 137  */
 138 void drm_bridge_connector_enable_hpd(struct drm_connector *connector)
 139 {
 140         struct drm_bridge_connector *bridge_connector =
 141                 to_drm_bridge_connector(connector);
 142         struct drm_bridge *hpd = bridge_connector->bridge_hpd;
 143
 144         if (hpd)
 145                 drm_bridge_hpd_enable(hpd, drm_bridge_connector_hpd_cb,
 146                                       bridge_connector);
 147 }
 148 EXPORT_SYMBOL_GPL(drm_bridge_connector_enable_hpd);
 149
 150 /**
 151  * drm_bridge_connector_disable_hpd - Disable hot-plug detection for the
 152  * connector
 153  * @connector: The DRM bridge connector
 154  *
 155  * This function disables hot-plug detection for the given bridge connector.
 156  * This is typically used by display drivers in their suspend handler.
 157  */
 158 void drm_bridge_connector_disable_hpd(struct drm_connector *connector)
 159 {
 160         struct drm_bridge_connector *bridge_connector =
 161                 to_drm_bridge_connector(connector);
 162         struct drm_bridge *hpd = bridge_connector->bridge_hpd;
 163
 164         if (hpd)
 165                 drm_bridge_hpd_disable(hpd);
 166 }
 167 EXPORT_SYMBOL_GPL(drm_bridge_connector_disable_hpd);
 168
 169 /* -----------------------------------------------------------------------------
 170  * Bridge Connector Functions
 171  */
 172
 173 static enum drm_connector_status
 174 drm_bridge_connector_detect(struct drm_connector *connector, bool force)
 175 {
 176         struct drm_bridge_connector *bridge_connector =
 177                 to_drm_bridge_connector(connector);
 178         struct drm_bridge *detect = bridge_connector->bridge_detect;
 179         enum drm_connector_status status;
 180
 181         if (detect) {
 182                 status = detect->funcs->detect(detect);
 183
 184                 drm_bridge_connector_hpd_notify(connector, status);
 185         } else {
 186                 switch (connector->connector_type) {
 187                 case DRM_MODE_CONNECTOR_DPI:
 188                 case DRM_MODE_CONNECTOR_LVDS:
 189                 case DRM_MODE_CONNECTOR_DSI:
 190                         status = connector_status_connected;
 191                         break;
 192                 default:
 193                         status = connector_status_unknown;
 194                         break;
 195                 }
 196         }
 197
 198         return status;
 199 }
 200
 201 static void drm_bridge_connector_destroy(struct drm_connector *connector)
 202 {
 203         struct drm_bridge_connector *bridge_connector =
 204                 to_drm_bridge_connector(connector);
 205
 206         if (bridge_connector->bridge_hpd) {
 207                 struct drm_bridge *hpd = bridge_connector->bridge_hpd;
 208
 209                 drm_bridge_hpd_disable(hpd);
 210         }
 211
 212         drm_connector_unregister(connector);
 213         drm_connector_cleanup(connector);
 214
 215         kfree(bridge_connector);
 216 }
 217
 218 static const struct drm_connector_funcs drm_bridge_connector_funcs = {
 219         .reset = drm_atomic_helper_connector_reset,
 220         .detect = drm_bridge_connector_detect,
 221         .fill_modes = drm_helper_probe_single_connector_modes,
 222         .destroy = drm_bridge_connector_destroy,
 223         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 224         .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 225 };
 226
 227 /* -----------------------------------------------------------------------------
 228  * Bridge Connector Helper Functions
 229  */
 230
 231 static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
 232                                                struct drm_bridge *bridge)
 233 {
 234         enum drm_connector_status status;
 235         struct edid *edid;
 236         int n;
 237
 238         status = drm_bridge_connector_detect(connector, false);
 239         if (status != connector_status_connected)
 240                 goto no_edid;
 241
 242         edid = bridge->funcs->get_edid(bridge, connector);
 243         if (!edid || !drm_edid_is_valid(edid)) {
 244                 kfree(edid);
 245                 goto no_edid;
 246         }
 247
 248         drm_connector_update_edid_property(connector, edid);
 249         n = drm_add_edid_modes(connector, edid);
 250
 251         kfree(edid);
 252         return n;
 253
 254 no_edid:
 255         drm_connector_update_edid_property(connector, NULL);
 256         return 0;
 257 }
 258
 259 static int drm_bridge_connector_get_modes(struct drm_connector *connector)
 260 {
 261         struct drm_bridge_connector *bridge_connector =
 262                 to_drm_bridge_connector(connector);
 263         struct drm_bridge *bridge;
 264
 265         /*
 266          * If display exposes EDID, then we parse that in the normal way to
 267          * build table of supported modes.
 268          */
 269         bridge = bridge_connector->bridge_edid;
 270         if (bridge)
 271                 return drm_bridge_connector_get_modes_edid(connector, bridge);
 272
 273         /*
 274          * Otherwise if the display pipeline reports modes (e.g. with a fixed
 275          * resolution panel or an analog TV output), query it.
 276          */
 277         bridge = bridge_connector->bridge_modes;
 278         if (bridge)
 279                 return bridge->funcs->get_modes(bridge, connector);
 280
 281         /*
 282          * We can't retrieve modes, which can happen for instance for a DVI or
 283          * VGA output with the DDC bus unconnected. The KMS core will add the
 284          * default modes.
 285          */
 286         return 0;
 287 }
 288
 289 static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
 290         .get_modes = drm_bridge_connector_get_modes,
 291         /* No need for .mode_valid(), the bridges are checked by the core. */
 292 };
 293
 294 /* -----------------------------------------------------------------------------
 295  * Bridge Connector Initialisation
 296  */
 297
 298 /**
 299  * drm_bridge_connector_init - Initialise a connector for a chain of bridges
 300  * @drm: the DRM device
 301  * @encoder: the encoder where the bridge chain starts
 302  *
 303  * Allocate, initialise and register a &drm_bridge_connector with the @drm
 304  * device. The connector is associated with a chain of bridges that starts at
 305  * the @encoder. All bridges in the chain shall report bridge operation flags
 306  * (&drm_bridge->ops) and bridge output type (&drm_bridge->type), and none of
 307  * them may create a DRM connector directly.
 308  *
 309  * Returns a pointer to the new connector on success, or a negative error
 310  * pointer otherwise.
 311  */
 312 struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 313                                                 struct drm_encoder *encoder)
 314 {
 315         struct drm_bridge_connector *bridge_connector;
 316         struct drm_connector *connector;
 317         struct i2c_adapter *ddc = NULL;
 318         struct drm_bridge *bridge;
 319         int connector_type;
 320
 321         bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
 322         if (!bridge_connector)
 323                 return ERR_PTR(-ENOMEM);
 324
 325         bridge_connector->encoder = encoder;
 326
 327         /*
 328          * TODO: Handle doublescan_allowed, stereo_allowed and
 329          * ycbcr_420_allowed.
 330          */
 331         connector = &bridge_connector->base;
 332         connector->interlace_allowed = true;
 333
 334         /*
 335          * Initialise connector status handling. First locate the furthest
 336          * bridges in the pipeline that support HPD and output detection. Then
 337          * initialise the connector polling mode, using HPD if available and
 338          * falling back to polling if supported. If neither HPD nor output
 339          * detection are available, we don't support hotplug detection at all.
 340          */
 341         connector_type = DRM_MODE_CONNECTOR_Unknown;
 342         drm_for_each_bridge_in_chain(encoder, bridge) {
 343                 if (!bridge->interlace_allowed)
 344                         connector->interlace_allowed = false;
 345
 346                 if (bridge->ops & DRM_BRIDGE_OP_EDID)
 347                         bridge_connector->bridge_edid = bridge;
 348                 if (bridge->ops & DRM_BRIDGE_OP_HPD)
 349                         bridge_connector->bridge_hpd = bridge;
 350                 if (bridge->ops & DRM_BRIDGE_OP_DETECT)
 351                         bridge_connector->bridge_detect = bridge;
 352                 if (bridge->ops & DRM_BRIDGE_OP_MODES)
 353                         bridge_connector->bridge_modes = bridge;
 354
 355                 if (!drm_bridge_get_next_bridge(bridge))
 356                         connector_type = bridge->type;
 357
 358                 if (bridge->ddc)
 359                         ddc = bridge->ddc;
 360         }
 361
 362         if (connector_type == DRM_MODE_CONNECTOR_Unknown) {
 363                 kfree(bridge_connector);
 364                 return ERR_PTR(-EINVAL);
 365         }
 366
 367         drm_connector_init_with_ddc(drm, connector, &drm_bridge_connector_funcs,
 368                                     connector_type, ddc);
 369         drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
 370
 371         if (bridge_connector->bridge_hpd)
 372                 connector->polled = DRM_CONNECTOR_POLL_HPD;
 373         else if (bridge_connector->bridge_detect)
 374                 connector->polled = DRM_CONNECTOR_POLL_CONNECT
 375                                   | DRM_CONNECTOR_POLL_DISCONNECT;
 376
 377         return connector;
 378 }
 379 EXPORT_SYMBOL_GPL(drm_bridge_connector_init);