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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 */
48struct 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
96static 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
110static 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 */
138void 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}
148EXPORT_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 */
158void 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}
167EXPORT_SYMBOL_GPL(drm_bridge_connector_disable_hpd);
168
169/* -----------------------------------------------------------------------------
170 * Bridge Connector Functions
171 */
172
173static enum drm_connector_status
174drm_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
202static 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
219static const struct drm_connector_funcs drm_bridge_connector_funcs = {
220 .reset = drm_atomic_helper_connector_reset,
221 .detect = drm_bridge_connector_detect,
222 .fill_modes = drm_helper_probe_single_connector_modes,
223 .destroy = drm_bridge_connector_destroy,
224 .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
225 .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
226};
227
228/* -----------------------------------------------------------------------------
229 * Bridge Connector Helper Functions
230 */
231
232static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
233 struct drm_bridge *bridge)
234{
235 enum drm_connector_status status;
236 struct edid *edid;
237 int n;
238
239 status = drm_bridge_connector_detect(connector, false);
240 if (status != connector_status_connected)
241 goto no_edid;
242
243 edid = bridge->funcs->get_edid(bridge, connector);
244 if (!drm_edid_is_valid(edid)) {
245 kfree(edid);
246 goto no_edid;
247 }
248
249 drm_connector_update_edid_property(connector, edid);
250 n = drm_add_edid_modes(connector, edid);
251
252 kfree(edid);
253 return n;
254
255no_edid:
256 drm_connector_update_edid_property(connector, NULL);
257 return 0;
258}
259
260static int drm_bridge_connector_get_modes(struct drm_connector *connector)
261{
262 struct drm_bridge_connector *bridge_connector =
263 to_drm_bridge_connector(connector);
264 struct drm_bridge *bridge;
265
266 /*
267 * If display exposes EDID, then we parse that in the normal way to
268 * build table of supported modes.
269 */
270 bridge = bridge_connector->bridge_edid;
271 if (bridge)
272 return drm_bridge_connector_get_modes_edid(connector, bridge);
273
274 /*
275 * Otherwise if the display pipeline reports modes (e.g. with a fixed
276 * resolution panel or an analog TV output), query it.
277 */
278 bridge = bridge_connector->bridge_modes;
279 if (bridge)
280 return bridge->funcs->get_modes(bridge, connector);
281
282 /*
283 * We can't retrieve modes, which can happen for instance for a DVI or
284 * VGA output with the DDC bus unconnected. The KMS core will add the
285 * default modes.
286 */
287 return 0;
288}
289
290static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
291 .get_modes = drm_bridge_connector_get_modes,
292 /* No need for .mode_valid(), the bridges are checked by the core. */
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 */
313struct 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;
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
363 if (connector_type == DRM_MODE_CONNECTOR_Unknown) {
364 kfree(bridge_connector);
365 return ERR_PTR(-EINVAL);
366 }
367
368 drm_connector_init_with_ddc(drm, connector, &drm_bridge_connector_funcs,
369 connector_type, ddc);
370 drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
371
372 if (bridge_connector->bridge_hpd)
373 connector->polled = DRM_CONNECTOR_POLL_HPD;
374 else if (bridge_connector->bridge_detect)
375 connector->polled = DRM_CONNECTOR_POLL_CONNECT
376 | DRM_CONNECTOR_POLL_DISCONNECT;
377
378 return connector;
379}
380EXPORT_SYMBOL_GPL(drm_bridge_connector_init);