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/of.h>
   9 #include <linux/property.h>
  10 #include <linux/slab.h>
  11
  12 #include <drm/drm_atomic_state_helper.h>
  13 #include <drm/drm_bridge.h>
  14 #include <drm/drm_bridge_connector.h>
  15 #include <drm/drm_connector.h>
  16 #include <drm/drm_device.h>
  17 #include <drm/drm_edid.h>
  18 #include <drm/drm_modeset_helper_vtables.h>
  19 #include <drm/drm_probe_helper.h>
  20
  21 /**
  22  * DOC: overview
  23  *
  24  * The DRM bridge connector helper object provides a DRM connector
  25  * implementation that wraps a chain of &struct drm_bridge. The connector
  26  * operations are fully implemented based on the operations of the bridges in
  27  * the chain, and don't require any intervention from the display controller
  28  * driver at runtime.
  29  *
  30  * To use the helper, display controller drivers create a bridge connector with
  31  * a call to drm_bridge_connector_init(). This associates the newly created
  32  * connector with the chain of bridges passed to the function and registers it
  33  * with the DRM device. At that point the connector becomes fully usable, no
  34  * further operation is needed.
  35  *
  36  * The DRM bridge connector operations are implemented based on the operations
  37  * provided by the bridges in the chain. Each connector operation is delegated
  38  * to the bridge closest to the connector (at the end of the chain) that
  39  * provides the relevant functionality.
  40  *
  41  * To make use of this helper, all bridges in the chain shall report bridge
  42  * operation flags (&drm_bridge->ops) and bridge output type
  43  * (&drm_bridge->type), as well as the DRM_BRIDGE_ATTACH_NO_CONNECTOR attach
  44  * flag (none of the bridges shall create a DRM connector directly).
  45  */
  46
  47 /**
  48  * struct drm_bridge_connector - A connector backed by a chain of bridges
  49  */
  50 struct drm_bridge_connector {
  51         /**
  52          * @base: The base DRM connector
  53          */
  54         struct drm_connector base;
  55         /**
  56          * @encoder:
  57          *
  58          * The encoder at the start of the bridges chain.
  59          */
  60         struct drm_encoder *encoder;
  61         /**
  62          * @bridge_edid:
  63          *
  64          * The last bridge in the chain (closest to the connector) that provides
  65          * EDID read support, if any (see &DRM_BRIDGE_OP_EDID).
  66          */
  67         struct drm_bridge *bridge_edid;
  68         /**
  69          * @bridge_hpd:
  70          *
  71          * The last bridge in the chain (closest to the connector) that provides
  72          * hot-plug detection notification, if any (see &DRM_BRIDGE_OP_HPD).
  73          */
  74         struct drm_bridge *bridge_hpd;
  75         /**
  76          * @bridge_detect:
  77          *
  78          * The last bridge in the chain (closest to the connector) that provides
  79          * connector detection, if any (see &DRM_BRIDGE_OP_DETECT).
  80          */
  81         struct drm_bridge *bridge_detect;
  82         /**
  83          * @bridge_modes:
  84          *
  85          * The last bridge in the chain (closest to the connector) that provides
  86          * connector modes detection, if any (see &DRM_BRIDGE_OP_MODES).
  87          */
  88         struct drm_bridge *bridge_modes;
  89 };
  90
  91 #define to_drm_bridge_connector(x) \
  92         container_of(x, struct drm_bridge_connector, base)
  93
  94 /* -----------------------------------------------------------------------------
  95  * Bridge Connector Hot-Plug Handling
  96  */
  97
  98 static void drm_bridge_connector_hpd_notify(struct drm_connector *connector,
  99                                             enum drm_connector_status status)
 100 {
 101         struct drm_bridge_connector *bridge_connector =
 102                 to_drm_bridge_connector(connector);
 103         struct drm_bridge *bridge;
 104
 105         /* Notify all bridges in the pipeline of hotplug events. */
 106         drm_for_each_bridge_in_chain(bridge_connector->encoder, bridge) {
 107                 if (bridge->funcs->hpd_notify)
 108                         bridge->funcs->hpd_notify(bridge, status);
 109         }
 110 }
 111
 112 static void drm_bridge_connector_handle_hpd(struct drm_bridge_connector *drm_bridge_connector,
 113                                             enum drm_connector_status status)
 114 {
 115         struct drm_connector *connector = &drm_bridge_connector->base;
 116         struct drm_device *dev = connector->dev;
 117
 118         mutex_lock(&dev->mode_config.mutex);
 119         connector->status = status;
 120         mutex_unlock(&dev->mode_config.mutex);
 121
 122         drm_bridge_connector_hpd_notify(connector, status);
 123
 124         drm_kms_helper_connector_hotplug_event(connector);
 125 }
 126
 127 static void drm_bridge_connector_hpd_cb(void *cb_data,
 128                                         enum drm_connector_status status)
 129 {
 130         drm_bridge_connector_handle_hpd(cb_data, status);
 131 }
 132
 133 static void drm_bridge_connector_oob_hotplug_event(struct drm_connector *connector,
 134                                                    enum drm_connector_status status)
 135 {
 136         struct drm_bridge_connector *bridge_connector =
 137                 to_drm_bridge_connector(connector);
 138
 139         drm_bridge_connector_handle_hpd(bridge_connector, status);
 140 }
 141
 142 static void drm_bridge_connector_enable_hpd(struct drm_connector *connector)
 143 {
 144         struct drm_bridge_connector *bridge_connector =
 145                 to_drm_bridge_connector(connector);
 146         struct drm_bridge *hpd = bridge_connector->bridge_hpd;
 147
 148         if (hpd)
 149                 drm_bridge_hpd_enable(hpd, drm_bridge_connector_hpd_cb,
 150                                       bridge_connector);
 151 }
 152
 153 static void drm_bridge_connector_disable_hpd(struct drm_connector *connector)
 154 {
 155         struct drm_bridge_connector *bridge_connector =
 156                 to_drm_bridge_connector(connector);
 157         struct drm_bridge *hpd = bridge_connector->bridge_hpd;
 158
 159         if (hpd)
 160                 drm_bridge_hpd_disable(hpd);
 161 }
 162
 163 /* -----------------------------------------------------------------------------
 164  * Bridge Connector Functions
 165  */
 166
 167 static enum drm_connector_status
 168 drm_bridge_connector_detect(struct drm_connector *connector, bool force)
 169 {
 170         struct drm_bridge_connector *bridge_connector =
 171                 to_drm_bridge_connector(connector);
 172         struct drm_bridge *detect = bridge_connector->bridge_detect;
 173         enum drm_connector_status status;
 174
 175         if (detect) {
 176                 status = detect->funcs->detect(detect);
 177
 178                 drm_bridge_connector_hpd_notify(connector, status);
 179         } else {
 180                 switch (connector->connector_type) {
 181                 case DRM_MODE_CONNECTOR_DPI:
 182                 case DRM_MODE_CONNECTOR_LVDS:
 183                 case DRM_MODE_CONNECTOR_DSI:
 184                 case DRM_MODE_CONNECTOR_eDP:
 185                         status = connector_status_connected;
 186                         break;
 187                 default:
 188                         status = connector_status_unknown;
 189                         break;
 190                 }
 191         }
 192
 193         return status;
 194 }
 195
 196 static void drm_bridge_connector_destroy(struct drm_connector *connector)
 197 {
 198         struct drm_bridge_connector *bridge_connector =
 199                 to_drm_bridge_connector(connector);
 200
 201         drm_connector_unregister(connector);
 202         drm_connector_cleanup(connector);
 203
 204         fwnode_handle_put(connector->fwnode);
 205
 206         kfree(bridge_connector);
 207 }
 208
 209 static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
 210                                               struct dentry *root)
 211 {
 212         struct drm_bridge_connector *bridge_connector =
 213                 to_drm_bridge_connector(connector);
 214         struct drm_encoder *encoder = bridge_connector->encoder;
 215         struct drm_bridge *bridge;
 216
 217         list_for_each_entry(bridge, &encoder->bridge_chain, chain_node) {
 218                 if (bridge->funcs->debugfs_init)
 219                         bridge->funcs->debugfs_init(bridge, root);
 220         }
 221 }
 222
 223 static const struct drm_connector_funcs drm_bridge_connector_funcs = {
 224         .reset = drm_atomic_helper_connector_reset,
 225         .detect = drm_bridge_connector_detect,
 226         .fill_modes = drm_helper_probe_single_connector_modes,
 227         .destroy = drm_bridge_connector_destroy,
 228         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 229         .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 230         .debugfs_init = drm_bridge_connector_debugfs_init,
 231         .oob_hotplug_event = drm_bridge_connector_oob_hotplug_event,
 232 };
 233
 234 /* -----------------------------------------------------------------------------
 235  * Bridge Connector Helper Functions
 236  */
 237
 238 static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
 239                                                struct drm_bridge *bridge)
 240 {
 241         enum drm_connector_status status;
 242         const struct drm_edid *drm_edid;
 243         int n;
 244
 245         status = drm_bridge_connector_detect(connector, false);
 246         if (status != connector_status_connected)
 247                 goto no_edid;
 248
 249         drm_edid = drm_bridge_edid_read(bridge, connector);
 250         if (!drm_edid_valid(drm_edid)) {
 251                 drm_edid_free(drm_edid);
 252                 goto no_edid;
 253         }
 254
 255         drm_edid_connector_update(connector, drm_edid);
 256         n = drm_edid_connector_add_modes(connector);
 257
 258         drm_edid_free(drm_edid);
 259         return n;
 260
 261 no_edid:
 262         drm_edid_connector_update(connector, NULL);
 263         return 0;
 264 }
 265
 266 static int drm_bridge_connector_get_modes(struct drm_connector *connector)
 267 {
 268         struct drm_bridge_connector *bridge_connector =
 269                 to_drm_bridge_connector(connector);
 270         struct drm_bridge *bridge;
 271
 272         /*
 273          * If display exposes EDID, then we parse that in the normal way to
 274          * build table of supported modes.
 275          */
 276         bridge = bridge_connector->bridge_edid;
 277         if (bridge)
 278                 return drm_bridge_connector_get_modes_edid(connector, bridge);
 279
 280         /*
 281          * Otherwise if the display pipeline reports modes (e.g. with a fixed
 282          * resolution panel or an analog TV output), query it.
 283          */
 284         bridge = bridge_connector->bridge_modes;
 285         if (bridge)
 286                 return bridge->funcs->get_modes(bridge, connector);
 287
 288         /*
 289          * We can't retrieve modes, which can happen for instance for a DVI or
 290          * VGA output with the DDC bus unconnected. The KMS core will add the
 291          * default modes.
 292          */
 293         return 0;
 294 }
 295
 296 static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
 297         .get_modes = drm_bridge_connector_get_modes,
 298         /* No need for .mode_valid(), the bridges are checked by the core. */
 299         .enable_hpd = drm_bridge_connector_enable_hpd,
 300         .disable_hpd = drm_bridge_connector_disable_hpd,
 301 };
 302
 303 /* -----------------------------------------------------------------------------
 304  * Bridge Connector Initialisation
 305  */
 306
 307 /**
 308  * drm_bridge_connector_init - Initialise a connector for a chain of bridges
 309  * @drm: the DRM device
 310  * @encoder: the encoder where the bridge chain starts
 311  *
 312  * Allocate, initialise and register a &drm_bridge_connector with the @drm
 313  * device. The connector is associated with a chain of bridges that starts at
 314  * the @encoder. All bridges in the chain shall report bridge operation flags
 315  * (&drm_bridge->ops) and bridge output type (&drm_bridge->type), and none of
 316  * them may create a DRM connector directly.
 317  *
 318  * Returns a pointer to the new connector on success, or a negative error
 319  * pointer otherwise.
 320  */
 321 struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 322                                                 struct drm_encoder *encoder)
 323 {
 324         struct drm_bridge_connector *bridge_connector;
 325         struct drm_connector *connector;
 326         struct i2c_adapter *ddc = NULL;
 327         struct drm_bridge *bridge, *panel_bridge = NULL;
 328         int connector_type;
 329         int ret;
 330
 331         bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
 332         if (!bridge_connector)
 333                 return ERR_PTR(-ENOMEM);
 334
 335         bridge_connector->encoder = encoder;
 336
 337         /*
 338          * TODO: Handle doublescan_allowed, stereo_allowed and
 339          * ycbcr_420_allowed.
 340          */
 341         connector = &bridge_connector->base;
 342         connector->interlace_allowed = true;
 343
 344         /*
 345          * Initialise connector status handling. First locate the furthest
 346          * bridges in the pipeline that support HPD and output detection. Then
 347          * initialise the connector polling mode, using HPD if available and
 348          * falling back to polling if supported. If neither HPD nor output
 349          * detection are available, we don't support hotplug detection at all.
 350          */
 351         connector_type = DRM_MODE_CONNECTOR_Unknown;
 352         drm_for_each_bridge_in_chain(encoder, bridge) {
 353                 if (!bridge->interlace_allowed)
 354                         connector->interlace_allowed = false;
 355
 356                 if (bridge->ops & DRM_BRIDGE_OP_EDID)
 357                         bridge_connector->bridge_edid = bridge;
 358                 if (bridge->ops & DRM_BRIDGE_OP_HPD)
 359                         bridge_connector->bridge_hpd = bridge;
 360                 if (bridge->ops & DRM_BRIDGE_OP_DETECT)
 361                         bridge_connector->bridge_detect = bridge;
 362                 if (bridge->ops & DRM_BRIDGE_OP_MODES)
 363                         bridge_connector->bridge_modes = bridge;
 364
 365                 if (!drm_bridge_get_next_bridge(bridge))
 366                         connector_type = bridge->type;
 367
 368 #ifdef CONFIG_OF
 369                 if (!drm_bridge_get_next_bridge(bridge) &&
 370                     bridge->of_node)
 371                         connector->fwnode = fwnode_handle_get(of_fwnode_handle(bridge->of_node));
 372 #endif
 373
 374                 if (bridge->ddc)
 375                         ddc = bridge->ddc;
 376
 377                 if (drm_bridge_is_panel(bridge))
 378                         panel_bridge = bridge;
 379         }
 380
 381         if (connector_type == DRM_MODE_CONNECTOR_Unknown) {
 382                 kfree(bridge_connector);
 383                 return ERR_PTR(-EINVAL);
 384         }
 385
 386         ret = drm_connector_init_with_ddc(drm, connector,
 387                                           &drm_bridge_connector_funcs,
 388                                           connector_type, ddc);
 389         if (ret) {
 390                 kfree(bridge_connector);
 391                 return ERR_PTR(ret);
 392         }
 393
 394         drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
 395
 396         if (bridge_connector->bridge_hpd)
 397                 connector->polled = DRM_CONNECTOR_POLL_HPD;
 398         else if (bridge_connector->bridge_detect)
 399                 connector->polled = DRM_CONNECTOR_POLL_CONNECT
 400                                   | DRM_CONNECTOR_POLL_DISCONNECT;
 401
 402         if (panel_bridge)
 403                 drm_panel_bridge_set_orientation(connector, panel_bridge);
 404
 405         return connector;
 406 }
 407 EXPORT_SYMBOL_GPL(drm_bridge_connector_init);