1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2019 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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
drm_bridge_connector_hpd_notify(struct drm_connector * connector,enum drm_connector_status status)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
drm_bridge_connector_hpd_cb(void * cb_data,enum drm_connector_status status)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 */
drm_bridge_connector_enable_hpd(struct drm_connector * connector)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 */
drm_bridge_connector_disable_hpd(struct drm_connector * connector)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
drm_bridge_connector_detect(struct drm_connector * connector,bool force)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 case DRM_MODE_CONNECTOR_eDP:
191 status = connector_status_connected;
192 break;
193 default:
194 status = connector_status_unknown;
195 break;
196 }
197 }
198
199 return status;
200 }
201
drm_bridge_connector_destroy(struct drm_connector * connector)202 static void drm_bridge_connector_destroy(struct drm_connector *connector)
203 {
204 struct drm_bridge_connector *bridge_connector =
205 to_drm_bridge_connector(connector);
206
207 if (bridge_connector->bridge_hpd) {
208 struct drm_bridge *hpd = bridge_connector->bridge_hpd;
209
210 drm_bridge_hpd_disable(hpd);
211 }
212
213 drm_connector_unregister(connector);
214 drm_connector_cleanup(connector);
215
216 kfree(bridge_connector);
217 }
218
drm_bridge_connector_debugfs_init(struct drm_connector * connector,struct dentry * root)219 static void drm_bridge_connector_debugfs_init(struct drm_connector *connector,
220 struct dentry *root)
221 {
222 struct drm_bridge_connector *bridge_connector =
223 to_drm_bridge_connector(connector);
224 struct drm_encoder *encoder = bridge_connector->encoder;
225 struct drm_bridge *bridge;
226
227 list_for_each_entry(bridge, &encoder->bridge_chain, chain_node) {
228 if (bridge->funcs->debugfs_init)
229 bridge->funcs->debugfs_init(bridge, root);
230 }
231 }
232
233 static const struct drm_connector_funcs drm_bridge_connector_funcs = {
234 .reset = drm_atomic_helper_connector_reset,
235 .detect = drm_bridge_connector_detect,
236 .fill_modes = drm_helper_probe_single_connector_modes,
237 .destroy = drm_bridge_connector_destroy,
238 .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
239 .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
240 .debugfs_init = drm_bridge_connector_debugfs_init,
241 };
242
243 /* -----------------------------------------------------------------------------
244 * Bridge Connector Helper Functions
245 */
246
drm_bridge_connector_get_modes_edid(struct drm_connector * connector,struct drm_bridge * bridge)247 static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
248 struct drm_bridge *bridge)
249 {
250 enum drm_connector_status status;
251 struct edid *edid;
252 int n;
253
254 status = drm_bridge_connector_detect(connector, false);
255 if (status != connector_status_connected)
256 goto no_edid;
257
258 edid = bridge->funcs->get_edid(bridge, connector);
259 if (!drm_edid_is_valid(edid)) {
260 kfree(edid);
261 goto no_edid;
262 }
263
264 drm_connector_update_edid_property(connector, edid);
265 n = drm_add_edid_modes(connector, edid);
266
267 kfree(edid);
268 return n;
269
270 no_edid:
271 drm_connector_update_edid_property(connector, NULL);
272 return 0;
273 }
274
drm_bridge_connector_get_modes(struct drm_connector * connector)275 static int drm_bridge_connector_get_modes(struct drm_connector *connector)
276 {
277 struct drm_bridge_connector *bridge_connector =
278 to_drm_bridge_connector(connector);
279 struct drm_bridge *bridge;
280
281 /*
282 * If display exposes EDID, then we parse that in the normal way to
283 * build table of supported modes.
284 */
285 bridge = bridge_connector->bridge_edid;
286 if (bridge)
287 return drm_bridge_connector_get_modes_edid(connector, bridge);
288
289 /*
290 * Otherwise if the display pipeline reports modes (e.g. with a fixed
291 * resolution panel or an analog TV output), query it.
292 */
293 bridge = bridge_connector->bridge_modes;
294 if (bridge)
295 return bridge->funcs->get_modes(bridge, connector);
296
297 /*
298 * We can't retrieve modes, which can happen for instance for a DVI or
299 * VGA output with the DDC bus unconnected. The KMS core will add the
300 * default modes.
301 */
302 return 0;
303 }
304
305 static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
306 .get_modes = drm_bridge_connector_get_modes,
307 /* No need for .mode_valid(), the bridges are checked by the core. */
308 };
309
310 /* -----------------------------------------------------------------------------
311 * Bridge Connector Initialisation
312 */
313
314 /**
315 * drm_bridge_connector_init - Initialise a connector for a chain of bridges
316 * @drm: the DRM device
317 * @encoder: the encoder where the bridge chain starts
318 *
319 * Allocate, initialise and register a &drm_bridge_connector with the @drm
320 * device. The connector is associated with a chain of bridges that starts at
321 * the @encoder. All bridges in the chain shall report bridge operation flags
322 * (&drm_bridge->ops) and bridge output type (&drm_bridge->type), and none of
323 * them may create a DRM connector directly.
324 *
325 * Returns a pointer to the new connector on success, or a negative error
326 * pointer otherwise.
327 */
drm_bridge_connector_init(struct drm_device * drm,struct drm_encoder * encoder)328 struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
329 struct drm_encoder *encoder)
330 {
331 struct drm_bridge_connector *bridge_connector;
332 struct drm_connector *connector;
333 struct i2c_adapter *ddc = NULL;
334 struct drm_bridge *bridge, *panel_bridge = NULL;
335 int connector_type;
336
337 bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
338 if (!bridge_connector)
339 return ERR_PTR(-ENOMEM);
340
341 bridge_connector->encoder = encoder;
342
343 /*
344 * TODO: Handle doublescan_allowed, stereo_allowed and
345 * ycbcr_420_allowed.
346 */
347 connector = &bridge_connector->base;
348 connector->interlace_allowed = true;
349
350 /*
351 * Initialise connector status handling. First locate the furthest
352 * bridges in the pipeline that support HPD and output detection. Then
353 * initialise the connector polling mode, using HPD if available and
354 * falling back to polling if supported. If neither HPD nor output
355 * detection are available, we don't support hotplug detection at all.
356 */
357 connector_type = DRM_MODE_CONNECTOR_Unknown;
358 drm_for_each_bridge_in_chain(encoder, bridge) {
359 if (!bridge->interlace_allowed)
360 connector->interlace_allowed = false;
361
362 if (bridge->ops & DRM_BRIDGE_OP_EDID)
363 bridge_connector->bridge_edid = bridge;
364 if (bridge->ops & DRM_BRIDGE_OP_HPD)
365 bridge_connector->bridge_hpd = bridge;
366 if (bridge->ops & DRM_BRIDGE_OP_DETECT)
367 bridge_connector->bridge_detect = bridge;
368 if (bridge->ops & DRM_BRIDGE_OP_MODES)
369 bridge_connector->bridge_modes = bridge;
370
371 if (!drm_bridge_get_next_bridge(bridge))
372 connector_type = bridge->type;
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 drm_connector_init_with_ddc(drm, connector, &drm_bridge_connector_funcs,
387 connector_type, ddc);
388 drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
389
390 if (bridge_connector->bridge_hpd) {
391 connector->polled = DRM_CONNECTOR_POLL_HPD;
392 drm_bridge_connector_enable_hpd(connector);
393 }
394 else if (bridge_connector->bridge_detect)
395 connector->polled = DRM_CONNECTOR_POLL_CONNECT
396 | DRM_CONNECTOR_POLL_DISCONNECT;
397
398 if (panel_bridge)
399 drm_panel_bridge_set_orientation(connector, panel_bridge);
400
401 return connector;
402 }
403 EXPORT_SYMBOL_GPL(drm_bridge_connector_init);
404
