[PATCH v29 32/33] ALSA: usb-audio: Allow for rediscovery of connected USB SND devices
From: Wesley Cheng <hidden>
Date: 2024-10-15 21:29:54
Also in:
alsa-devel, linux-arm-msm, linux-devicetree, linux-doc, linux-sound, linux-usb, lkml
Subsystem:
sound, the rest · Maintainers:
Jaroslav Kysela, Takashi Iwai, Linus Torvalds
In case of notifying SND platform drivers of connection events, some of these use cases, such as offloading, require an ASoC USB backend device to be initialized before the events can be handled. If the USB backend device has not yet been probed, this leads to missing initial USB audio device connection events. Expose an API that traverses the usb_chip array for connected devices, and to call the respective connection callback registered to the SND platform driver. Signed-off-by: Wesley Cheng <redacted> --- sound/usb/card.c | 21 +++++++++++++++++++++ sound/usb/card.h | 2 ++ sound/usb/qcom/qc_audio_offload.c | 2 ++ 3 files changed, 25 insertions(+)
diff --git a/sound/usb/card.c b/sound/usb/card.c
index 326292f37841..1f21d11416f9 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c@@ -155,6 +155,27 @@ int snd_usb_unregister_platform_ops(void) } EXPORT_SYMBOL_GPL(snd_usb_unregister_platform_ops); +/* + * in case the platform driver was not ready at the time of USB SND + * device connect, expose an API to discover all connected USB devices + * so it can populate any dependent resources/structures. + */ +void snd_usb_rediscover_devices(void) +{ + int i; + + guard(mutex)(®ister_mutex); + + if (!platform_ops || !platform_ops->connect_cb) + return; + + for (i = 0; i < SNDRV_CARDS; i++) { + if (usb_chip[i]) + platform_ops->connect_cb(usb_chip[i]); + } +} +EXPORT_SYMBOL_GPL(snd_usb_rediscover_devices); + /* * Checks to see if requested audio profile, i.e sample rate, # of * channels, etc... is supported by the substream associated to the
diff --git a/sound/usb/card.h b/sound/usb/card.h
index d8b8522e1613..94404c24d240 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h@@ -222,4 +222,6 @@ snd_usb_find_suppported_substream(int card_idx, struct snd_pcm_hw_params *params int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops); int snd_usb_unregister_platform_ops(void); + +void snd_usb_rediscover_devices(void); #endif /* __USBAUDIO_CARD_H */
diff --git a/sound/usb/qcom/qc_audio_offload.c b/sound/usb/qcom/qc_audio_offload.c
index c4165fc88fd1..7839be4cbf32 100644
--- a/sound/usb/qcom/qc_audio_offload.c
+++ b/sound/usb/qcom/qc_audio_offload.c@@ -1935,6 +1935,8 @@ static int __init qc_usb_audio_offload_init(void) if (ret < 0) goto release_qmi; + snd_usb_rediscover_devices(); + return 0; release_qmi: