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usb: gadget: u_audio: Rate ctl notifies about current srate (0=stopped)

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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@ivitera.com>
Link: https://lore.kernel.org/r/20220121155308.48794-8-pavel.hofman@ivitera.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pavel Hofman 2022-01-21 16:53:05 +01:00 committed by Greg Kroah-Hartman
parent 695d39ffc2
commit 8fe9a03f43
1 changed files with 27 additions and 1 deletions
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28
drivers/usb/gadget/function/u_audio.c
View file

@ -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;
}