On Mon, Dec 20, 2021 at 10:11:25PM +0100, Pavel Hofman wrote: > The Playback/Capture ctl currently reports rate value set by USB > control selector UAC2_CS_CONTROL_SAM_FREQ (fixed for UAC1). When the > host has stopped 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> > --- > drivers/usb/gadget/function/u_audio.c | 46 ++++++++++++--------------- > 1 file changed, 21 insertions(+), 25 deletions(-) > > diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c > index e737a104156d..a6293415c071 100644 > --- a/drivers/usb/gadget/function/u_audio.c > +++ b/drivers/usb/gadget/function/u_audio.c > @@ -64,6 +64,7 @@ struct uac_rtd_params { > int mute; > > struct snd_kcontrol *snd_kctl_rate; /* read-only current rate */ > + int rep_srate; /* srate reported by snd_kctl_rate */ > > spinlock_t lock; /* lock for control transfers */ > > @@ -496,8 +497,6 @@ static inline void free_ep_fback(struct uac_rtd_params *prm, struct usb_ep *ep) > int u_audio_set_capture_srate(struct g_audio *audio_dev, int srate) > { > struct uac_params *params = &audio_dev->params; > - struct snd_uac_chip *uac = audio_dev->uac; > - struct uac_rtd_params *prm = &uac->c_prm; > int i; > > dev_dbg(&audio_dev->gadget->dev, "%s: srate %d\n", __func__, srate); > @@ -516,8 +515,6 @@ EXPORT_SYMBOL_GPL(u_audio_set_capture_srate); > > int u_audio_set_playback_srate(struct g_audio *audio_dev, int srate) > { > - struct snd_uac_chip *uac = audio_dev->uac; > - struct uac_rtd_params *prm = &uac->p_prm; > struct uac_params *params = &audio_dev->params; > int i; > > @@ -535,6 +532,18 @@ int u_audio_set_playback_srate(struct g_audio *audio_dev, int srate) > } > EXPORT_SYMBOL_GPL(u_audio_set_playback_srate); > > +static void set_reported_srate(struct uac_rtd_params *prm, int srate) > +{ > + struct snd_kcontrol *kctl = prm->snd_kctl_rate; > + > + if (prm->rep_srate != srate) { > + prm->rep_srate = srate; > + snd_ctl_notify(prm->uac->card, SNDRV_CTL_EVENT_MASK_VALUE, > + &kctl->id); > + pr_debug("Setting '%s' to %d", kctl->id.name, srate); > + } > +} > + > int u_audio_start_capture(struct g_audio *audio_dev) > { > struct snd_uac_chip *uac = audio_dev->uac; > @@ -574,6 +583,8 @@ int u_audio_start_capture(struct g_audio *audio_dev) > dev_err(dev, "%s:%d Error!\n", __func__, __LINE__); > } > > + set_reported_srate(&uac->c_prm, params->c_srate); > + > ep_fback = audio_dev->in_ep_fback; > if (!ep_fback) > return 0; > @@ -619,6 +630,7 @@ void u_audio_stop_capture(struct g_audio *audio_dev) > { > struct snd_uac_chip *uac = audio_dev->uac; > > + set_reported_srate(&uac->c_prm, 0); > 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); > @@ -691,6 +703,8 @@ int u_audio_start_playback(struct g_audio *audio_dev) > dev_err(dev, "%s:%d Error!\n", __func__, __LINE__); > } > > + set_reported_srate(&uac->p_prm, params->p_srate); > + > return 0; > } > EXPORT_SYMBOL_GPL(u_audio_start_playback); > @@ -699,6 +713,7 @@ void u_audio_stop_playback(struct g_audio *audio_dev) > { > struct snd_uac_chip *uac = audio_dev->uac; > > + set_reported_srate(&uac->p_prm, 0); > free_ep(&uac->p_prm, audio_dev->in_ep); > } > EXPORT_SYMBOL_GPL(u_audio_stop_playback); > @@ -1001,19 +1016,6 @@ static int get_max_srate(const int *srates) > return max_srate; > } > > -static int get_min_srate(const int *srates) > -{ > - int i, min_srate = INT_MAX; > - > - for (i = 0; i < UAC_MAX_RATES; i++) { > - if (srates[i] == 0) > - break; > - if (srates[i] < min_srate) > - min_srate = srates[i]; > - } > - return min_srate; > -} > - > static int uac_pcm_rate_info(struct snd_kcontrol *kcontrol, > struct snd_ctl_elem_info *uinfo) > { > @@ -1030,7 +1032,7 @@ static int uac_pcm_rate_info(struct snd_kcontrol *kcontrol, > srates = params->c_srates; > else > srates = params->p_srates; > - uinfo->value.integer.min = get_min_srate(srates); > + uinfo->value.integer.min = 0; > uinfo->value.integer.max = get_max_srate(srates); > return 0; > } > @@ -1039,14 +1041,8 @@ static int uac_pcm_rate_get(struct snd_kcontrol *kcontrol, > struct snd_ctl_elem_value *ucontrol) > { > struct uac_rtd_params *prm = snd_kcontrol_chip(kcontrol); > - struct snd_uac_chip *uac = prm->uac; > - struct g_audio *audio_dev = uac->audio_dev; > - struct uac_params *params = &audio_dev->params; > > - if (prm == &uac->c_prm) > - ucontrol->value.integer.value[0] = params->c_srate; > - else > - ucontrol->value.integer.value[0] = params->p_srate; > + ucontrol->value.integer.value[0] = prm->rep_srate; This function was only added in patch 2, wouldn't it be better to add the rate to the right place at that point? I think uac_params is supposed to be the fixed (user selected) parameters whereas uac_rtd_params are the varying values that may be affected by the host, so the current rate belongs in uac_rtd_params. > return 0; > } > -- > 2.25.1 >
