diff mbox series

[v21,27/39] ASoC: Introduce SND kcontrols to select sound card and PCM device

Message ID 20240507195116.9464-28-quic_wcheng@quicinc.com
State Superseded
Headers show
Series Introduce QC USB SND audio offloading support | expand

Commit Message

Wesley Cheng May 7, 2024, 7:51 p.m. UTC 
Add SND kcontrol to SOC USB, which will allow for userpsace to determine
which USB card number and PCM device to offload.  This allows for userspace
to potentially tag an alternate path for a specific USB SND card and PCM
device.  Previously, control was absent, and the offload path would be
enabled on the last USB SND device which was connected.  This logic will
continue to be applicable if no mixer input is received for specific device
selection.

An example to configure the offload device using tinymix:
tinymix -D 0 set 'USB Offload Playback Route Select' 1 0

The above command will configure the offload path to utilize card#1 and PCM
stream#0.

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
---
 include/sound/soc-usb.h |  16 ++++
 sound/soc/soc-usb.c     | 157 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 173 insertions(+)

Comments

Pierre-Louis Bossart May 7, 2024, 9:26 p.m. UTC | #1 
On 5/7/24 14:51, Wesley Cheng wrote:
> Add SND kcontrol to SOC USB, which will allow for userpsace to determine
> which USB card number and PCM device to offload.  This allows for userspace
> to potentially tag an alternate path for a specific USB SND card and PCM
> device.  Previously, control was absent, and the offload path would be
> enabled on the last USB SND device which was connected.  This logic will
> continue to be applicable if no mixer input is received for specific device
> selection.
> 
> An example to configure the offload device using tinymix:
> tinymix -D 0 set 'USB Offload Playback Route Select' 1 0
> 
> The above command will configure the offload path to utilize card#1 and PCM
> stream#0.

I don't know how this is usable in practice. Using card indices is
really hard to do, it depends on the order in which devices are
plugged-in...
Wesley Cheng May 9, 2024, 12:10 a.m. UTC | #2 
Hi Pierre,

On 5/7/2024 2:26 PM, Pierre-Louis Bossart wrote:
> 
> 
> On 5/7/24 14:51, Wesley Cheng wrote:
>> Add SND kcontrol to SOC USB, which will allow for userpsace to determine
>> which USB card number and PCM device to offload.  This allows for userspace
>> to potentially tag an alternate path for a specific USB SND card and PCM
>> device.  Previously, control was absent, and the offload path would be
>> enabled on the last USB SND device which was connected.  This logic will
>> continue to be applicable if no mixer input is received for specific device
>> selection.
>>
>> An example to configure the offload device using tinymix:
>> tinymix -D 0 set 'USB Offload Playback Route Select' 1 0
>>
>> The above command will configure the offload path to utilize card#1 and PCM
>> stream#0.
> 
> I don't know how this is usable in practice. Using card indices is
> really hard to do, it depends on the order in which devices are
> plugged-in...

How are the existing mechanisms handling USB audio devices, or what is 
the identifier being used?

Thanks
Wesley Cheng
Wesley Cheng May 9, 2024, 10:32 p.m. UTC | #3 
Hi Pierre,

On 5/9/2024 6:07 AM, Pierre-Louis Bossart wrote:
> 
> 
> On 5/8/24 19:10, Wesley Cheng wrote:
>> Hi Pierre,
>>
>> On 5/7/2024 2:26 PM, Pierre-Louis Bossart wrote:
>>>
>>>
>>> On 5/7/24 14:51, Wesley Cheng wrote:
>>>> Add SND kcontrol to SOC USB, which will allow for userpsace to determine
>>>> which USB card number and PCM device to offload.  This allows for
>>>> userspace
>>>> to potentially tag an alternate path for a specific USB SND card and PCM
>>>> device.  Previously, control was absent, and the offload path would be
>>>> enabled on the last USB SND device which was connected.  This logic will
>>>> continue to be applicable if no mixer input is received for specific
>>>> device
>>>> selection.
>>>>
>>>> An example to configure the offload device using tinymix:
>>>> tinymix -D 0 set 'USB Offload Playback Route Select' 1 0
>>>>
>>>> The above command will configure the offload path to utilize card#1
>>>> and PCM
>>>> stream#0.
>>>
>>> I don't know how this is usable in practice. Using card indices is
>>> really hard to do, it depends on the order in which devices are
>>> plugged-in...
>>
>> How are the existing mechanisms handling USB audio devices, or what is
>> the identifier being used?
> 
> Well it's a mess, that's why I asked.
> 
> There are configuration work-arounds to make sure that 'local'
> accessories are handled first and get repeatable card indices.
> 

So is the intention of the configuration aspect you're thinking of to 
have an entry that maps a USB device based on some identifier, which 
will take the offload path by default?

IMO, the concept of this selection of card and PCM device should happen 
after the application discovers a USB device that is offload capable. 
For example, maybe the application will use the USB VID/PID to lookup an 
entry within the configuration.  If some offload tag is present, it can 
further determine which card and PCM devices are associated w/ the USB 
device?  Although this is under the assumption the application has 
insight to the USB sysfs.

> But between USB devices I guess the rule is 'anything goes'. Even if
> there are two devices connected at boot, the index allocation will
> depend on probe order. The card names are not necessarily super-useful
> either, i.e. yesterday I was confused by an USB card named "CODEC"
> without any details.

That device is very informative :D

Thanks
Wesley Cheng
diff mbox series

Patch

diff --git a/include/sound/soc-usb.h b/include/sound/soc-usb.h
index 8f754a44a79e..56f74dbb3600 100644
--- a/include/sound/soc-usb.h
+++ b/include/sound/soc-usb.h
@@ -6,6 +6,12 @@ 
 #ifndef __LINUX_SND_SOC_USB_H
 #define __LINUX_SND_SOC_USB_H
 
+enum snd_soc_usb_kctl {
+	SND_SOC_USB_KCTL_CARD_ROUTE,
+	SND_SOC_USB_KCTL_PCM_ROUTE,
+	SND_SOC_USB_KCTL_MAX,
+};
+
 /**
  * struct snd_soc_usb_device
  * @card_idx - sound card index associated with USB device
@@ -24,16 +30,26 @@  struct snd_soc_usb_device {
  * struct snd_soc_usb
  * @list - list head for SND SOC struct list
  * @component - reference to ASoC component
+ * @kctl - list of kcontrols created
  * @num_supported_streams - number of supported concurrent sessions
  * @connection_status_cb - callback to notify connection events
+ * @put_offload_dev - callback to select USB sound card/PCM device
+ * @get_offload_dev - callback to fetch selected USB sound card/PCM device
  * @priv_data - driver data
  **/
 struct snd_soc_usb {
 	struct list_head list;
 	struct snd_soc_component *component;
+	struct snd_kcontrol *kctl[SND_SOC_USB_KCTL_MAX];
 	unsigned int num_supported_streams;
 	int (*connection_status_cb)(struct snd_soc_usb *usb,
 			struct snd_soc_usb_device *sdev, bool connected);
+	int (*put_offload_dev)(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *ucontrol,
+			       enum snd_soc_usb_kctl type);
+	int (*get_offload_dev)(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *ucontrol,
+			       enum snd_soc_usb_kctl type);
 	void *priv_data;
 };
 
diff --git a/sound/soc/soc-usb.c b/sound/soc/soc-usb.c
index 304455b62958..6f8fd9acd5dd 100644
--- a/sound/soc/soc-usb.c
+++ b/sound/soc/soc-usb.c
@@ -15,6 +15,9 @@  static struct device_node *snd_soc_find_phandle(struct device *dev)
 {
 	struct device_node *node;
 
+	if (!dev)
+		return ERR_PTR(-ENODEV);
+
 	node = of_parse_phandle(dev->of_node, "usb-soc-be", 0);
 	if (!node)
 		return ERR_PTR(-ENODEV);
@@ -57,6 +60,152 @@  static struct snd_soc_usb *snd_soc_find_usb_ctx(struct device *dev)
 	return ctx ? ctx : NULL;
 }
 
+/* SOC USB sound kcontrols */
+static int soc_usb_put_offload_pcm_dev(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+	int ret = 0;
+
+	mutex_lock(&ctx_mutex);
+	if (ctx && ctx->put_offload_dev)
+		ret = ctx->put_offload_dev(kcontrol, ucontrol,
+						SND_SOC_USB_KCTL_PCM_ROUTE);
+	mutex_unlock(&ctx_mutex);
+
+	return ret;
+}
+
+static int soc_usb_get_offload_pcm_dev(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+	int ret = 0;
+
+	ucontrol->value.integer.value[0] = -1;
+
+	mutex_lock(&ctx_mutex);
+	if (ctx && ctx->get_offload_dev)
+		ret = ctx->get_offload_dev(kcontrol, ucontrol,
+						SND_SOC_USB_KCTL_PCM_ROUTE);
+	mutex_unlock(&ctx_mutex);
+
+	return ret;
+
+}
+
+static int soc_usb_put_offload_card_dev(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+	int ret = 0;
+
+	mutex_lock(&ctx_mutex);
+	if (ctx && ctx->put_offload_dev)
+		ret = ctx->put_offload_dev(kcontrol, ucontrol,
+						SND_SOC_USB_KCTL_CARD_ROUTE);
+	mutex_unlock(&ctx_mutex);
+
+	return ret;
+}
+
+static int soc_usb_get_offload_card_dev(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct snd_soc_usb *ctx = snd_soc_usb_ctx_lookup(component->dev->of_node);
+	int ret = 0;
+
+	ucontrol->value.integer.value[0] = -1;
+
+	mutex_lock(&ctx_mutex);
+	if (ctx && ctx->get_offload_dev)
+		ret = ctx->get_offload_dev(kcontrol, ucontrol,
+						SND_SOC_USB_KCTL_CARD_ROUTE);
+	mutex_unlock(&ctx_mutex);
+
+	return ret;
+
+}
+
+static int soc_usb_offload_pcm_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = -1;
+	/* Arbitrary max value, as there is no 'limit' on number of PCM devices */
+	uinfo->value.integer.max = 0xff;
+
+	return 0;
+}
+
+static int soc_usb_offload_card_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = -1;
+	uinfo->value.integer.max = SNDRV_CARDS;
+
+	return 0;
+}
+
+static const struct snd_kcontrol_new soc_usb_kcontrols[] = {
+	[SND_SOC_USB_KCTL_CARD_ROUTE] = {
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
+		.name = "USB Offload Playback Route Card Select",
+		.info = soc_usb_offload_card_info,
+		.get = soc_usb_get_offload_card_dev,
+		.put = soc_usb_put_offload_card_dev,
+	},
+	[SND_SOC_USB_KCTL_PCM_ROUTE] = {
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
+		.name = "USB Offload Playback Route PCM Select",
+		.info = soc_usb_offload_pcm_info,
+		.get = soc_usb_get_offload_pcm_dev,
+		.put = soc_usb_put_offload_pcm_dev,
+	},
+};
+
+static int snd_soc_usb_control_remove(struct snd_soc_usb *usb)
+{
+	struct snd_soc_component *component = usb->component;
+	int i;
+
+	for (i = 0; i < SND_SOC_USB_KCTL_MAX; i++) {
+		if (usb->kctl[i]) {
+			snd_ctl_remove(component->card->snd_card,
+					usb->kctl[i]);
+			snd_ctl_free_one(usb->kctl[i]);
+			usb->kctl[i] = NULL;
+		}
+	}
+
+	return 0;
+}
+
+static int snd_soc_usb_control_init(struct snd_soc_usb *usb)
+{
+	struct snd_soc_component *component = usb->component;
+	int ret;
+	int i;
+
+	for (i = 0; i < SND_SOC_USB_KCTL_MAX; i++) {
+		usb->kctl[i] = snd_ctl_new1(&soc_usb_kcontrols[i], component);
+		ret = snd_ctl_add(component->card->snd_card, usb->kctl[i]);
+		if (ret < 0)
+			return ret;
+	}
+
+	return ret;
+}
+
 /**
  * snd_soc_usb_get_components_tag() - Retrieve SOC USB component tag
  * @playback: direction of audio stream
@@ -169,6 +318,12 @@  EXPORT_SYMBOL_GPL(snd_soc_usb_free_port);
  */
 int snd_soc_usb_add_port(struct snd_soc_usb *usb)
 {
+	int ret;
+
+	ret = snd_soc_usb_control_init(usb);
+	if (ret < 0)
+		return ret;
+
 	mutex_lock(&ctx_mutex);
 	list_add_tail(&usb->list, &usb_ctx_list);
 	mutex_unlock(&ctx_mutex);
@@ -198,6 +353,8 @@  int snd_soc_usb_remove_port(struct snd_soc_usb *usb)
 	}
 	mutex_unlock(&ctx_mutex);
 
+	snd_soc_usb_control_remove(usb);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(snd_soc_usb_remove_port);