The Playback/Capture ctl currently reports rate value set by USB control selector UAC2_CS_CONTROL_SAM_FREQ (fixed for UAC1). When the stops playback/capture, the reported value does not change. The gadget side has no information whether the host has started/stopped capture/playback. This patch sets the value reported by the respective rate ctl to zero when the host side has stopped playback/capture. Also, it calls snd_ctl_notify when start/stop occurs, so that a subscribed client can act appropriately. Tests have confirmed that USB hosts change UAC2_CS_CONTROL_SAM_FREQ before switching altsetting to activate playback/capture, resulting in correct order (params->c/p_srate is set to requested rate before u_audio_start_capture/playback is called). The gadget rate notifications are used by user-space audio gadget controller gaudio_ctl https://github.com/pavhofman/gaudio_ctl. Signed-off-by: Pavel Hofman <pavel.hofman@xxxxxxxxxxx> --- v3: * using prm->srate instead of params->c_srate/p_srate due to the added commit "[v3] usb: gadget: u_audio: Move dynamic srate from params to rtd" --- drivers/usb/gadget/function/u_audio.c | 28 ++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c index 283a449a9538..fab1bc439002 100644 --- a/drivers/usb/gadget/function/u_audio.c +++ b/drivers/usb/gadget/function/u_audio.c @@ -65,6 +65,7 @@ struct uac_rtd_params { struct snd_kcontrol *snd_kctl_rate; /* read-only current rate */ int srate; /* selected samplerate */ + int active; /* playback/capture running */ spinlock_t lock; /* lock for control transfers */ @@ -490,6 +491,21 @@ static inline void free_ep_fback(struct uac_rtd_params *prm, struct usb_ep *ep) dev_err(uac->card->dev, "%s:%d Error!\n", __func__, __LINE__); } +static void set_active(struct uac_rtd_params *prm, bool active) +{ + // notifying through the Rate ctrl + struct snd_kcontrol *kctl = prm->snd_kctl_rate; + unsigned long flags; + + spin_lock_irqsave(&prm->lock, flags); + if (prm->active != active) { + prm->active = active; + snd_ctl_notify(prm->uac->card, SNDRV_CTL_EVENT_MASK_VALUE, + &kctl->id); + } + spin_unlock_irqrestore(&prm->lock, flags); +} + int u_audio_set_capture_srate(struct g_audio *audio_dev, int srate) { struct uac_params *params = &audio_dev->params; @@ -607,6 +623,8 @@ int u_audio_start_capture(struct g_audio *audio_dev) dev_err(dev, "%s:%d Error!\n", __func__, __LINE__); } + set_active(&uac->c_prm, true); + ep_fback = audio_dev->in_ep_fback; if (!ep_fback) return 0; @@ -652,6 +670,7 @@ void u_audio_stop_capture(struct g_audio *audio_dev) { struct snd_uac_chip *uac = audio_dev->uac; + set_active(&uac->c_prm, false); if (audio_dev->in_ep_fback) free_ep_fback(&uac->c_prm, audio_dev->in_ep_fback); free_ep(&uac->c_prm, audio_dev->out_ep); @@ -723,6 +742,8 @@ int u_audio_start_playback(struct g_audio *audio_dev) dev_err(dev, "%s:%d Error!\n", __func__, __LINE__); } + set_active(&uac->p_prm, true); + return 0; } EXPORT_SYMBOL_GPL(u_audio_start_playback); @@ -731,6 +752,7 @@ void u_audio_stop_playback(struct g_audio *audio_dev) { struct snd_uac_chip *uac = audio_dev->uac; + set_active(&uac->p_prm, false); free_ep(&uac->p_prm, audio_dev->in_ep); } EXPORT_SYMBOL_GPL(u_audio_stop_playback); @@ -1074,7 +1096,11 @@ static int u_audio_rate_get(struct snd_kcontrol *kcontrol, unsigned long flags; spin_lock_irqsave(&prm->lock, flags); - ucontrol->value.integer.value[0] = prm->srate; + if (prm->active) + ucontrol->value.integer.value[0] = prm->srate; + else + /* not active: reporting zero rate */ + ucontrol->value.integer.value[0] = 0; spin_unlock_irqrestore(&prm->lock, flags); return 0; } -- 2.25.1
