1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * vimc-streamer.c Virtual Media Controller Driver
4 *
5 * Copyright (C) 2018 Lucas A. M. Magalhães <lucmaga@gmail.com>
6 *
7 */
8
9 #include <linux/init.h>
10 #include <linux/freezer.h>
11 #include <linux/kthread.h>
12
13 #include "vimc-streamer.h"
14
15 /**
16 * vimc_get_source_entity - get the entity connected with the first sink pad
17 *
18 * @ent: reference media_entity
19 *
20 * Helper function that returns the media entity containing the source pad
21 * linked with the first sink pad from the given media entity pad list.
22 *
23 * Return: The source pad or NULL, if it wasn't found.
24 */
vimc_get_source_entity(struct media_entity * ent)25 static struct media_entity *vimc_get_source_entity(struct media_entity *ent)
26 {
27 struct media_pad *pad;
28 int i;
29
30 for (i = 0; i < ent->num_pads; i++) {
31 if (ent->pads[i].flags & MEDIA_PAD_FL_SOURCE)
32 continue;
33 pad = media_pad_remote_pad_first(&ent->pads[i]);
34 return pad ? pad->entity : NULL;
35 }
36 return NULL;
37 }
38
39 /**
40 * vimc_streamer_pipeline_terminate - Disable stream in all ved in stream
41 *
42 * @stream: the pointer to the stream structure with the pipeline to be
43 * disabled.
44 *
45 * Calls s_stream to disable the stream in each entity of the pipeline
46 *
47 */
vimc_streamer_pipeline_terminate(struct vimc_stream * stream)48 static void vimc_streamer_pipeline_terminate(struct vimc_stream *stream)
49 {
50 struct vimc_ent_device *ved;
51 struct v4l2_subdev *sd;
52
53 while (stream->pipe_size) {
54 stream->pipe_size--;
55 ved = stream->ved_pipeline[stream->pipe_size];
56 stream->ved_pipeline[stream->pipe_size] = NULL;
57
58 if (!is_media_entity_v4l2_subdev(ved->ent))
59 continue;
60
61 sd = media_entity_to_v4l2_subdev(ved->ent);
62 v4l2_subdev_call(sd, video, s_stream, 0);
63 }
64 }
65
66 /**
67 * vimc_streamer_pipeline_init - Initializes the stream structure
68 *
69 * @stream: the pointer to the stream structure to be initialized
70 * @ved: the pointer to the vimc entity initializing the stream
71 *
72 * Initializes the stream structure. Walks through the entity graph to
73 * construct the pipeline used later on the streamer thread.
74 * Calls vimc_streamer_s_stream() to enable stream in all entities of
75 * the pipeline.
76 *
77 * Return: 0 if success, error code otherwise.
78 */
vimc_streamer_pipeline_init(struct vimc_stream * stream,struct vimc_ent_device * ved)79 static int vimc_streamer_pipeline_init(struct vimc_stream *stream,
80 struct vimc_ent_device *ved)
81 {
82 struct media_entity *entity;
83 struct video_device *vdev;
84 struct v4l2_subdev *sd;
85 int ret = 0;
86
87 stream->pipe_size = 0;
88 while (stream->pipe_size < VIMC_STREAMER_PIPELINE_MAX_SIZE) {
89 if (!ved) {
90 vimc_streamer_pipeline_terminate(stream);
91 return -EINVAL;
92 }
93 stream->ved_pipeline[stream->pipe_size++] = ved;
94
95 if (is_media_entity_v4l2_subdev(ved->ent)) {
96 sd = media_entity_to_v4l2_subdev(ved->ent);
97 ret = v4l2_subdev_call(sd, video, s_stream, 1);
98 if (ret && ret != -ENOIOCTLCMD) {
99 dev_err(ved->dev, "subdev_call error %s\n",
100 ved->ent->name);
101 vimc_streamer_pipeline_terminate(stream);
102 return ret;
103 }
104 }
105
106 entity = vimc_get_source_entity(ved->ent);
107 /* Check if the end of the pipeline was reached */
108 if (!entity) {
109 /* the first entity of the pipe should be source only */
110 if (!vimc_is_source(ved->ent)) {
111 dev_err(ved->dev,
112 "first entity in the pipe '%s' is not a source\n",
113 ved->ent->name);
114 vimc_streamer_pipeline_terminate(stream);
115 return -EPIPE;
116 }
117 return 0;
118 }
119
120 /* Get the next device in the pipeline */
121 if (is_media_entity_v4l2_subdev(entity)) {
122 sd = media_entity_to_v4l2_subdev(entity);
123 ved = v4l2_get_subdevdata(sd);
124 } else {
125 vdev = container_of(entity,
126 struct video_device,
127 entity);
128 ved = video_get_drvdata(vdev);
129 }
130 }
131
132 vimc_streamer_pipeline_terminate(stream);
133 return -EINVAL;
134 }
135
136 /**
137 * vimc_streamer_thread - Process frames through the pipeline
138 *
139 * @data: vimc_stream struct of the current stream
140 *
141 * From the source to the sink, gets a frame from each subdevice and send to
142 * the next one of the pipeline at a fixed framerate.
143 *
144 * Return:
145 * Always zero (created as ``int`` instead of ``void`` to comply with
146 * kthread API).
147 */
vimc_streamer_thread(void * data)148 static int vimc_streamer_thread(void *data)
149 {
150 struct vimc_stream *stream = data;
151 u8 *frame = NULL;
152 int i;
153
154 set_freezable();
155
156 for (;;) {
157 try_to_freeze();
158 if (kthread_should_stop())
159 break;
160
161 for (i = stream->pipe_size - 1; i >= 0; i--) {
162 frame = stream->ved_pipeline[i]->process_frame(
163 stream->ved_pipeline[i], frame);
164 if (!frame || IS_ERR(frame))
165 break;
166 }
167 //wait for 60hz
168 set_current_state(TASK_UNINTERRUPTIBLE);
169 schedule_timeout(HZ / 60);
170 }
171
172 return 0;
173 }
174
175 /**
176 * vimc_streamer_s_stream - Start/stop the streaming on the media pipeline
177 *
178 * @stream: the pointer to the stream structure of the current stream
179 * @ved: pointer to the vimc entity of the entity of the stream
180 * @enable: flag to determine if stream should start/stop
181 *
182 * When starting, check if there is no ``stream->kthread`` allocated. This
183 * should indicate that a stream is already running. Then, it initializes the
184 * pipeline, creates and runs a kthread to consume buffers through the pipeline.
185 * When stopping, analogously check if there is a stream running, stop the
186 * thread and terminates the pipeline.
187 *
188 * Return: 0 if success, error code otherwise.
189 */
vimc_streamer_s_stream(struct vimc_stream * stream,struct vimc_ent_device * ved,int enable)190 int vimc_streamer_s_stream(struct vimc_stream *stream,
191 struct vimc_ent_device *ved,
192 int enable)
193 {
194 int ret;
195
196 if (!stream || !ved)
197 return -EINVAL;
198
199 if (enable) {
200 if (stream->kthread)
201 return 0;
202
203 ret = vimc_streamer_pipeline_init(stream, ved);
204 if (ret)
205 return ret;
206
207 stream->kthread = kthread_run(vimc_streamer_thread, stream,
208 "vimc-streamer thread");
209
210 if (IS_ERR(stream->kthread)) {
211 ret = PTR_ERR(stream->kthread);
212 dev_err(ved->dev, "kthread_run failed with %d\n", ret);
213 vimc_streamer_pipeline_terminate(stream);
214 stream->kthread = NULL;
215 return ret;
216 }
217
218 } else {
219 if (!stream->kthread)
220 return 0;
221
222 ret = kthread_stop(stream->kthread);
223 /*
224 * kthread_stop returns -EINTR in cases when streamon was
225 * immediately followed by streamoff, and the thread didn't had
226 * a chance to run. Ignore errors to stop the stream in the
227 * pipeline.
228 */
229 if (ret)
230 dev_dbg(ved->dev, "kthread_stop returned '%d'\n", ret);
231
232 stream->kthread = NULL;
233
234 vimc_streamer_pipeline_terminate(stream);
235 }
236
237 return 0;
238 }
239