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 static void drm_bridge_connector_enable_hpd(struct drm_connector *connector)
 132 {
 133         struct drm_bridge_connector *bridge_connector =
 134                 to_drm_bridge_connector(connector);
 135         struct drm_bridge *hpd = bridge_connector->bridge_hpd;
 136
 137         if (hpd)
 138                 drm_bridge_hpd_enable(hpd, drm_bridge_connector_hpd_cb,
 139                                       bridge_connector);
 140 }
 141
 142 static void drm_bridge_connector_disable_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_disable(hpd);
 150 }
 151
 152 /* -----------------------------------------------------------------------------
 153  * Bridge Connector Functions
 154  */
 155
 156 static enum drm_connector_status
 157 drm_bridge_connector_detect(struct drm_connector *connector, bool force)
 158 {
 159         struct drm_bridge_connector *bridge_connector =
 160                 to_drm_bridge_connector(connector);
 161         struct drm_bridge *detect = bridge_connector->bridge_detect;
 162         enum drm_connector_status status;
 163
 164         if (detect) {
 165                 status = detect->funcs->detect(detect);
 166
 167                 drm_bridge_connector_hpd_notify(connector, status);
 168         } else {
 169                 switch (connector->connector_type) {
 170                 case DRM_MODE_CONNECTOR_DPI:
 171                 case DRM_MODE_CONNECTOR_LVDS:
 172                 case DRM_MODE_CONNECTOR_DSI:
 173                 case DRM_MODE_CONNECTOR_eDP:
 174                         status = connector_status_connected;
 175                         break;
 176                 default:
 177                         status = connector_status_unknown;
 178                         break;
 179                 }
 180         }
 181
 182         return status;
 183 }
 184
 185 static void drm_bridge_connector_destroy(struct drm_connector *connector)
 186 {
 187         struct drm_bridge_connector *bridge_connector =
 188                 to_drm_bridge_connector(connector);
 189
 190         if (bridge_connector->bridge_hpd) {
 191                 struct drm_bridge *hpd = bridge_connector->bridge_hpd;
 192
 193                 drm_bridge_hpd_disable(hpd);
 194         }
 195
 196         drm_connector_unregister(connector);
 197         drm_connector_cleanup(connector);
 198
 199         kfree(bridge_connector);
 200 }
 201
 202 static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
 203                                               struct dentry *root)
 204 {
 205         struct drm_bridge_connector *bridge_connector =
 206                 to_drm_bridge_connector(connector);
 207         struct drm_encoder *encoder = bridge_connector->encoder;
 208         struct drm_bridge *bridge;
 209
 210         list_for_each_entry(bridge, &encoder->bridge_chain, chain_node) {
 211                 if (bridge->funcs->debugfs_init)
 212                         bridge->funcs->debugfs_init(bridge, root);
 213         }
 214 }
 215
 216 static const struct drm_connector_funcs drm_bridge_connector_funcs = {
 217         .reset = drm_atomic_helper_connector_reset,
 218         .detect = drm_bridge_connector_detect,
 219         .fill_modes = drm_helper_probe_single_connector_modes,
 220         .destroy = drm_bridge_connector_destroy,
 221         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 222         .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 223         .debugfs_init = drm_bridge_connector_debugfs_init,
 224 };
 225
 226 /* -----------------------------------------------------------------------------
 227  * Bridge Connector Helper Functions
 228  */
 229
 230 static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
 231                                                struct drm_bridge *bridge)
 232 {
 233         enum drm_connector_status status;
 234         struct edid *edid;
 235         int n;
 236
 237         status = drm_bridge_connector_detect(connector, false);
 238         if (status != connector_status_connected)
 239                 goto no_edid;
 240
 241         edid = bridge->funcs->get_edid(bridge, connector);
 242         if (!drm_edid_is_valid(edid)) {
 243                 kfree(edid);
 244                 goto no_edid;
 245         }
 246
 247         drm_connector_update_edid_property(connector, edid);
 248         n = drm_add_edid_modes(connector, edid);
 249
 250         kfree(edid);
 251         return n;
 252
 253 no_edid:
 254         drm_connector_update_edid_property(connector, NULL);
 255         return 0;
 256 }
 257
 258 static int drm_bridge_connector_get_modes(struct drm_connector *connector)
 259 {
 260         struct drm_bridge_connector *bridge_connector =
 261                 to_drm_bridge_connector(connector);
 262         struct drm_bridge *bridge;
 263
 264         /*
 265          * If display exposes EDID, then we parse that in the normal way to
 266          * build table of supported modes.
 267          */
 268         bridge = bridge_connector->bridge_edid;
 269         if (bridge)
 270                 return drm_bridge_connector_get_modes_edid(connector, bridge);
 271
 272         /*
 273          * Otherwise if the display pipeline reports modes (e.g. with a fixed
 274          * resolution panel or an analog TV output), query it.
 275          */
 276         bridge = bridge_connector->bridge_modes;
 277         if (bridge)
 278                 return bridge->funcs->get_modes(bridge, connector);
 279
 280         /*
 281          * We can't retrieve modes, which can happen for instance for a DVI or
 282          * VGA output with the DDC bus unconnected. The KMS core will add the
 283          * default modes.
 284          */
 285         return 0;
 286 }
 287
 288 static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
 289         .get_modes = drm_bridge_connector_get_modes,
 290         /* No need for .mode_valid(), the bridges are checked by the core. */
 291         .enable_hpd = drm_bridge_connector_enable_hpd,
 292         .disable_hpd = drm_bridge_connector_disable_hpd,
 293 };
 294
 295 /* -----------------------------------------------------------------------------
 296  * Bridge Connector Initialisation
 297  */
 298
 299 /**
 300  * drm_bridge_connector_init - Initialise a connector for a chain of bridges
 301  * @drm: the DRM device
 302  * @encoder: the encoder where the bridge chain starts
 303  *
 304  * Allocate, initialise and register a &drm_bridge_connector with the @drm
 305  * device. The connector is associated with a chain of bridges that starts at
 306  * the @encoder. All bridges in the chain shall report bridge operation flags
 307  * (&drm_bridge->ops) and bridge output type (&drm_bridge->type), and none of
 308  * them may create a DRM connector directly.
 309  *
 310  * Returns a pointer to the new connector on success, or a negative error
 311  * pointer otherwise.
 312  */
 313 struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 314                                                 struct drm_encoder *encoder)
 315 {
 316         struct drm_bridge_connector *bridge_connector;
 317         struct drm_connector *connector;
 318         struct i2c_adapter *ddc = NULL;
 319         struct drm_bridge *bridge, *panel_bridge = NULL;
 320         int connector_type;
 321
 322         bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
 323         if (!bridge_connector)
 324                 return ERR_PTR(-ENOMEM);
 325
 326         bridge_connector->encoder = encoder;
 327
 328         /*
 329          * TODO: Handle doublescan_allowed, stereo_allowed and
 330          * ycbcr_420_allowed.
 331          */
 332         connector = &bridge_connector->base;
 333         connector->interlace_allowed = true;
 334
 335         /*
 336          * Initialise connector status handling. First locate the furthest
 337          * bridges in the pipeline that support HPD and output detection. Then
 338          * initialise the connector polling mode, using HPD if available and
 339          * falling back to polling if supported. If neither HPD nor output
 340          * detection are available, we don't support hotplug detection at all.
 341          */
 342         connector_type = DRM_MODE_CONNECTOR_Unknown;
 343         drm_for_each_bridge_in_chain(encoder, bridge) {
 344                 if (!bridge->interlace_allowed)
 345                         connector->interlace_allowed = false;
 346
 347                 if (bridge->ops & DRM_BRIDGE_OP_EDID)
 348                         bridge_connector->bridge_edid = bridge;
 349                 if (bridge->ops & DRM_BRIDGE_OP_HPD)
 350                         bridge_connector->bridge_hpd = bridge;
 351                 if (bridge->ops & DRM_BRIDGE_OP_DETECT)
 352                         bridge_connector->bridge_detect = bridge;
 353                 if (bridge->ops & DRM_BRIDGE_OP_MODES)
 354                         bridge_connector->bridge_modes = bridge;
 355
 356                 if (!drm_bridge_get_next_bridge(bridge))
 357                         connector_type = bridge->type;
 358
 359                 if (bridge->ddc)
 360                         ddc = bridge->ddc;
 361
 362                 if (drm_bridge_is_panel(bridge))
 363                         panel_bridge = bridge;
 364         }
 365
 366         if (connector_type == DRM_MODE_CONNECTOR_Unknown) {
 367                 kfree(bridge_connector);
 368                 return ERR_PTR(-EINVAL);
 369         }
 370
 371         drm_connector_init_with_ddc(drm, connector, &drm_bridge_connector_funcs,
 372                                     connector_type, ddc);
 373         drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
 374
 375         if (bridge_connector->bridge_hpd)
 376                 connector->polled = DRM_CONNECTOR_POLL_HPD;
 377         else if (bridge_connector->bridge_detect)
 378                 connector->polled = DRM_CONNECTOR_POLL_CONNECT
 379                                   | DRM_CONNECTOR_POLL_DISCONNECT;
 380
 381         if (panel_bridge)
 382                 drm_panel_bridge_set_orientation(connector, panel_bridge);
 383
 384         return connector;
 385 }
 386 EXPORT_SYMBOL_GPL(drm_bridge_connector_init);