sound/usb/stream.c

Source file repositories/reference/linux-study-clean/sound/usb/stream.c

File Facts

System: Linux kernel
Corpus path: sound/usb/stream.c
Extension: .c
Size: 34044 bytes
Lines: 1292
Domain: Driver Families
Bucket: sound/usb
Inferred role: Driver Families: implementation source
Status: source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.
Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
Allocates kernel memory; connect allocation flags and lifetime to context constraints.
Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

linux/init.h
linux/slab.h
linux/usb.h
linux/usb/audio.h
linux/usb/audio-v2.h
linux/usb/audio-v3.h
sound/core.h
sound/pcm.h
sound/control.h
sound/tlv.h
usbaudio.h
card.h
proc.h
quirks.h
endpoint.h
pcm.h
helper.h
format.h
clock.h
stream.h
power.h
media.h

Detected Declarations

function audioformat_free
function free_substream
function snd_usb_audio_stream_free
function snd_usb_audio_pcm_free
function snd_usb_init_substream
function usb_chmap_ctl_info
function have_dup_chmap
function list_for_each_entry_continue_reverse
function usb_chmap_ctl_tlv
function usb_chmap_ctl_get
function add_chmap
function snd_usb_add_audio_stream
function list_for_each_entry
function parse_uac_endpoint_attributes
function snd_usb_find_input_terminal_descriptor
function snd_usb_find_output_terminal_descriptor
function audio_format_alloc_init
function snd_usb_get_audioformat_uac12
function snd_usb_get_audioformat_uac3
function __snd_usb_parse_audio_interface
function snd_usb_parse_audio_interface

Annotated Snippet

if (cs_type == UAC3_CHANNEL_INFORMATION) {
			struct uac3_cluster_information_segment_descriptor *is = p;
			unsigned char map;

			if (cs_len < sizeof(*is))
				break;

			/*
			 * TODO: this conversion is not complete, update it
			 * after adding UAC3 values to asound.h
			 * NOTE: not all UAC3 channel relationship have a
			 * direct ALSA chmap equivalent.
			 */
			switch (is->bChRelationship) {
			case UAC3_CH_MONO:
				map = SNDRV_CHMAP_MONO;
				break;
			case UAC3_CH_LEFT:
			case UAC3_CH_FRONT_LEFT:
			case UAC3_CH_HEADPHONE_LEFT:
				map = SNDRV_CHMAP_FL;
				break;
			case UAC3_CH_RIGHT:
			case UAC3_CH_FRONT_RIGHT:
			case UAC3_CH_HEADPHONE_RIGHT:
				map = SNDRV_CHMAP_FR;
				break;
			case UAC3_CH_FRONT_CENTER:
				map = SNDRV_CHMAP_FC;
				break;
			case UAC3_CH_FRONT_LEFT_OF_CENTER:
				map = SNDRV_CHMAP_FLC;
				break;
			case UAC3_CH_FRONT_RIGHT_OF_CENTER:
				map = SNDRV_CHMAP_FRC;
				break;
			case UAC3_CH_FRONT_WIDE_LEFT:
				map = SNDRV_CHMAP_FLW;
				break;
			case UAC3_CH_FRONT_WIDE_RIGHT:
				map = SNDRV_CHMAP_FRW;
				break;
			case UAC3_CH_SIDE_LEFT:
				map = SNDRV_CHMAP_SL;
				break;
			case UAC3_CH_SIDE_RIGHT:
				map = SNDRV_CHMAP_SR;
				break;
			case UAC3_CH_BACK_LEFT:
				map = SNDRV_CHMAP_RL;
				break;
			case UAC3_CH_BACK_RIGHT:
				map = SNDRV_CHMAP_RR;
				break;
			case UAC3_CH_BACK_CENTER:
				map = SNDRV_CHMAP_RC;
				break;
			case UAC3_CH_BACK_LEFT_OF_CENTER:
				map = SNDRV_CHMAP_RLC;
				break;
			case UAC3_CH_BACK_RIGHT_OF_CENTER:
				map = SNDRV_CHMAP_RRC;
				break;
			case UAC3_CH_TOP_CENTER:
				map = SNDRV_CHMAP_TC;
				break;
			case UAC3_CH_TOP_FRONT_LEFT:
				map = SNDRV_CHMAP_TFL;
				break;
			case UAC3_CH_TOP_FRONT_RIGHT:
				map = SNDRV_CHMAP_TFR;
				break;
			case UAC3_CH_TOP_FRONT_CENTER:
				map = SNDRV_CHMAP_TFC;
				break;
			case UAC3_CH_TOP_FRONT_LOC:
				map = SNDRV_CHMAP_TFLC;
				break;
			case UAC3_CH_TOP_FRONT_ROC:
				map = SNDRV_CHMAP_TFRC;
				break;
			case UAC3_CH_TOP_SIDE_LEFT:
				map = SNDRV_CHMAP_TSL;
				break;
			case UAC3_CH_TOP_SIDE_RIGHT:
				map = SNDRV_CHMAP_TSR;
				break;
			case UAC3_CH_TOP_BACK_LEFT:
				map = SNDRV_CHMAP_TRL;
				break;

Annotation

Immediate include surface: `linux/init.h`, `linux/slab.h`, `linux/usb.h`, `linux/usb/audio.h`, `linux/usb/audio-v2.h`, `linux/usb/audio-v3.h`, `sound/core.h`, `sound/pcm.h`.
Detected declarations: `function audioformat_free`, `function free_substream`, `function snd_usb_audio_stream_free`, `function snd_usb_audio_pcm_free`, `function snd_usb_init_substream`, `function usb_chmap_ctl_info`, `function have_dup_chmap`, `function list_for_each_entry_continue_reverse`, `function usb_chmap_ctl_tlv`, `function usb_chmap_ctl_get`.
Atlas domain: Driver Families / sound/usb.
Implementation status: source implementation candidate.
This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.
Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.