66354f18fe
Media Device Allocator API to allows multiple drivers share a media device. This API solves a very common use-case for media devices where one physical device (an USB stick) provides both audio and video. When such media device exposes a standard USB Audio class, a proprietary Video class, two or more independent drivers will share a single physical USB bridge. In such cases, it is necessary to coordinate access to the shared resource. Using this API, drivers can allocate a media device with the shared struct device as the key. Once the media device is allocated by a driver, other drivers can get a reference to it. The media device is released when all the references are released. Change the ALSA driver to use the Media Controller API to share media resources with DVB, and V4L2 drivers on a AU0828 media device. The Media Controller specific initialization is done after sound card is registered. ALSA creates Media interface and entity function graph nodes for Control, Mixer, PCM Playback, and PCM Capture devices. snd_usb_hw_params() will call Media Controller enable source handler interface to request the media resource. If resource request is granted, it will release it from snd_usb_hw_free(). If resource is busy, -EBUSY is returned. Media specific cleanup is done in usb_audio_disconnect(). Reviewed-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Shuah Khan <shuah@kernel.org> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
75 lines
2.4 KiB
C
75 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* media.h - Media Controller specific ALSA driver code
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*
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* Copyright (c) 2019 Shuah Khan <shuah@kernel.org>
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*
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*/
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/*
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* This file adds Media Controller support to the ALSA driver
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* to use the Media Controller API to share the tuner with DVB
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* and V4L2 drivers that control the media device.
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*
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* The media device is created based on the existing quirks framework.
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* Using this approach, the media controller API usage can be added for
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* a specific device.
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*/
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#ifndef __MEDIA_H
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#ifdef CONFIG_SND_USB_AUDIO_USE_MEDIA_CONTROLLER
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#include <linux/media.h>
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#include <media/media-device.h>
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#include <media/media-entity.h>
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#include <media/media-dev-allocator.h>
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#include <sound/asound.h>
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struct media_ctl {
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struct media_device *media_dev;
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struct media_entity media_entity;
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struct media_intf_devnode *intf_devnode;
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struct media_link *intf_link;
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struct media_pad media_pad;
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struct media_pipeline media_pipe;
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};
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/*
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* One source pad each for SNDRV_PCM_STREAM_CAPTURE and
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* SNDRV_PCM_STREAM_PLAYBACK. One for sink pad to link
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* to AUDIO Source
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*/
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#define MEDIA_MIXER_PAD_MAX (SNDRV_PCM_STREAM_LAST + 2)
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struct media_mixer_ctl {
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struct media_device *media_dev;
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struct media_entity media_entity;
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struct media_intf_devnode *intf_devnode;
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struct media_link *intf_link;
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struct media_pad media_pad[MEDIA_MIXER_PAD_MAX];
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struct media_pipeline media_pipe;
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};
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int snd_media_device_create(struct snd_usb_audio *chip,
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struct usb_interface *iface);
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void snd_media_device_delete(struct snd_usb_audio *chip);
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int snd_media_stream_init(struct snd_usb_substream *subs, struct snd_pcm *pcm,
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int stream);
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void snd_media_stream_delete(struct snd_usb_substream *subs);
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int snd_media_start_pipeline(struct snd_usb_substream *subs);
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void snd_media_stop_pipeline(struct snd_usb_substream *subs);
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#else
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static inline int snd_media_device_create(struct snd_usb_audio *chip,
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struct usb_interface *iface)
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{ return 0; }
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static inline void snd_media_device_delete(struct snd_usb_audio *chip) { }
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static inline int snd_media_stream_init(struct snd_usb_substream *subs,
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struct snd_pcm *pcm, int stream)
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{ return 0; }
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static inline void snd_media_stream_delete(struct snd_usb_substream *subs) { }
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static inline int snd_media_start_pipeline(struct snd_usb_substream *subs)
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{ return 0; }
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static inline void snd_media_stop_pipeline(struct snd_usb_substream *subs) { }
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#endif
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#endif /* __MEDIA_H */
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