Commit 40c73b30 authored by Ruslan Bilovol's avatar Ruslan Bilovol Committed by Greg Kroah-Hartman
Browse files

usb: gadget: f_uac2: add adaptive sync support for capture 



Current f_uac2 USB OUT (aka 'capture') synchronization
implements 'ASYNC' scenario which means USB Gadget has
it's own freerunning clock and can update Host about
real clock frequency through feedback endpoint so Host
can align number of samples sent to the USB gadget to
prevent overruns/underruns

In case if Gadget can has no it's internal clock and
can consume audio samples at any rate (for example,
on the Gadget side someone records audio directly to
a file, or audio samples are played through an
external DAC as soon as they arrive), UAC2 spec
suggests 'ADAPTIVE' synchronization type.

Change UAC2 driver to make it configurable through
additional 'c_sync' configfs file.

Default remains 'asynchronous' with possibility to
switch it to 'adaptive'

Signed-off-by: default avatarRuslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: default avatarJerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20210603220104.1216001-3-jbrunet@baylibre.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 24f779da

Documentation/ABI/testing/configfs-usb-gadget-uac2

+1 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ Description: 
		c_chmask   capture channel mask

		c_srate    capture sampling rate

		c_ssize    capture sample size (bytes)

		c_sync     capture synchronization type (async/adaptive)

		p_chmask   playback channel mask

		p_srate    playback sampling rate

		p_ssize    playback sample size (bytes)

Documentation/usb/gadget-testing.rst

+1 −0
Original line number Diff line number Diff line
@@ -728,6 +728,7 @@ The uac2 function provides these attributes in its function directory: 
	c_chmask	capture channel mask

	c_srate		capture sampling rate

	c_ssize		capture sample size (bytes)

	c_sync		capture synchronization type (async/adaptive)

	p_chmask	playback channel mask

	p_srate		playback sampling rate

	p_ssize		playback sample size (bytes)

drivers/usb/gadget/function/f_uac2.c

+91 −9
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 


#define EPIN_EN(_opts) ((_opts)->p_chmask != 0)

#define EPOUT_EN(_opts) ((_opts)->c_chmask != 0)

#define EPOUT_FBACK_IN_EN(_opts) ((_opts)->c_sync == USB_ENDPOINT_SYNC_ASYNC)



struct f_uac2 {

	struct g_audio g_audio;
@@ -240,7 +241,7 @@ static struct usb_interface_descriptor std_as_out_if1_desc = { 
	.bDescriptorType = USB_DT_INTERFACE,



	.bAlternateSetting = 1,

	.bNumEndpoints = 2,

	.bNumEndpoints = 1,

	.bInterfaceClass = USB_CLASS_AUDIO,

	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,

	.bInterfaceProtocol = UAC_VERSION_2,
@@ -273,7 +274,7 @@ static struct usb_endpoint_descriptor fs_epout_desc = { 
	.bDescriptorType = USB_DT_ENDPOINT,



	.bEndpointAddress = USB_DIR_OUT,

	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,

	/* .bmAttributes = DYNAMIC */

	/* .wMaxPacketSize = DYNAMIC */

	.bInterval = 1,

};
@@ -282,7 +283,7 @@ static struct usb_endpoint_descriptor hs_epout_desc = { 
	.bLength = USB_DT_ENDPOINT_SIZE,

	.bDescriptorType = USB_DT_ENDPOINT,



	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,

	/* .bmAttributes = DYNAMIC */

	/* .wMaxPacketSize = DYNAMIC */

	.bInterval = 4,

};
@@ -292,7 +293,7 @@ static struct usb_endpoint_descriptor ss_epout_desc = { 
	.bDescriptorType = USB_DT_ENDPOINT,



	.bEndpointAddress = USB_DIR_OUT,

	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,

	/* .bmAttributes = DYNAMIC */

	/* .wMaxPacketSize = DYNAMIC */

	.bInterval = 4,

};
@@ -649,6 +650,8 @@ static void setup_headers(struct f_uac2_opts *opts, 
			headers[i++] = USBDHDR(epout_desc_comp);



		headers[i++] = USBDHDR(&as_iso_out_desc);



		if (EPOUT_FBACK_IN_EN(opts))

			headers[i++] = USBDHDR(epin_fback_desc);

	}

	if (EPIN_EN(opts)) {
@@ -820,6 +823,23 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn) 
		std_as_out_if1_desc.bInterfaceNumber = ret;

		uac2->as_out_intf = ret;

		uac2->as_out_alt = 0;



		if (EPOUT_FBACK_IN_EN(uac2_opts)) {

			fs_epout_desc.bmAttributes =

			  USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC;

			hs_epout_desc.bmAttributes =

			  USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC;

			ss_epout_desc.bmAttributes =

			  USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC;

			std_as_out_if1_desc.bNumEndpoints++;

		} else {

			fs_epout_desc.bmAttributes =

			  USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ADAPTIVE;

			hs_epout_desc.bmAttributes =

			  USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ADAPTIVE;

			ss_epout_desc.bmAttributes =

			  USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ADAPTIVE;

		}

	}



	if (EPIN_EN(uac2_opts)) {
@@ -883,13 +903,16 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn) 
			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);

			return -ENODEV;

		}

		if (EPOUT_FBACK_IN_EN(uac2_opts)) {

			agdev->in_ep_fback = usb_ep_autoconfig(gadget,

						       &fs_epin_fback_desc);

			if (!agdev->in_ep_fback) {

			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);

				dev_err(dev, "%s:%d Error!\n",

					__func__, __LINE__);

				return -ENODEV;

			}

		}

	}



	if (EPIN_EN(uac2_opts)) {

		agdev->in_ep = usb_ep_autoconfig(gadget, &fs_epin_desc);
@@ -1242,11 +1265,68 @@ end: \ 
									\

CONFIGFS_ATTR(f_uac2_opts_, name)



#define UAC2_ATTRIBUTE_SYNC(name)					\

static ssize_t f_uac2_opts_##name##_show(struct config_item *item,	\

					 char *page)			\

{									\

	struct f_uac2_opts *opts = to_f_uac2_opts(item);		\

	int result;							\

	char *str;							\

									\

	mutex_lock(&opts->lock);					\

	switch (opts->name) {						\

	case USB_ENDPOINT_SYNC_ASYNC:					\

		str = "async";						\

		break;							\

	case USB_ENDPOINT_SYNC_ADAPTIVE:				\

		str = "adaptive";					\

		break;							\

	default:							\

		str = "unknown";					\

		break;							\

	}								\

	result = sprintf(page, "%s\n", str);				\

	mutex_unlock(&opts->lock);					\

									\

	return result;							\

}									\

									\

static ssize_t f_uac2_opts_##name##_store(struct config_item *item,	\

					  const char *page, size_t len)	\

{									\

	struct f_uac2_opts *opts = to_f_uac2_opts(item);		\

	int ret = 0;							\

									\

	mutex_lock(&opts->lock);					\

	if (opts->refcnt) {						\

		ret = -EBUSY;						\

		goto end;						\

	}								\

									\

	if (!strncmp(page, "async", 5))					\

		opts->name = USB_ENDPOINT_SYNC_ASYNC;			\

	else if (!strncmp(page, "adaptive", 8))				\

		opts->name = USB_ENDPOINT_SYNC_ADAPTIVE;		\

	else {								\

		ret = -EINVAL;						\

		goto end;						\

	}								\

									\

	ret = len;							\

									\

end:									\

	mutex_unlock(&opts->lock);					\

	return ret;							\

}									\

									\

CONFIGFS_ATTR(f_uac2_opts_, name)



UAC2_ATTRIBUTE(p_chmask);

UAC2_ATTRIBUTE(p_srate);

UAC2_ATTRIBUTE(p_ssize);

UAC2_ATTRIBUTE(c_chmask);

UAC2_ATTRIBUTE(c_srate);

UAC2_ATTRIBUTE_SYNC(c_sync);

UAC2_ATTRIBUTE(c_ssize);

UAC2_ATTRIBUTE(req_number);
@@ -1257,6 +1337,7 @@ static struct configfs_attribute *f_uac2_attrs[] = { 
	&f_uac2_opts_attr_c_chmask,

	&f_uac2_opts_attr_c_srate,

	&f_uac2_opts_attr_c_ssize,

	&f_uac2_opts_attr_c_sync,

	&f_uac2_opts_attr_req_number,

	NULL,

};
@@ -1295,6 +1376,7 @@ static struct usb_function_instance *afunc_alloc_inst(void) 
	opts->c_chmask = UAC2_DEF_CCHMASK;

	opts->c_srate = UAC2_DEF_CSRATE;

	opts->c_ssize = UAC2_DEF_CSSIZE;

	opts->c_sync = UAC2_DEF_CSYNC;

	opts->req_number = UAC2_DEF_REQ_NUM;

	return &opts->func_inst;

}

drivers/usb/gadget/function/u_uac2.h

+2 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#define UAC2_DEF_CCHMASK 0x3

#define UAC2_DEF_CSRATE 64000

#define UAC2_DEF_CSSIZE 2

#define UAC2_DEF_CSYNC		USB_ENDPOINT_SYNC_ASYNC

#define UAC2_DEF_REQ_NUM 2



struct f_uac2_opts {
@@ -31,6 +32,7 @@ struct f_uac2_opts { 
	int				c_chmask;

	int				c_srate;

	int				c_ssize;

	int				c_sync;

	int				req_number;

	bool				bound;