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Code Issues Releases Wiki Activity

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

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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: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20210603220104.1216001-3-jbrunet@baylibre.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ruslan Bilovol 2021-06-04 00:01:03 +02:00 committed by Greg Kroah-Hartman
parent 24f779dac8
commit 40c73b3054
4 changed files with 95 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
Documentation/ABI/testing/configfs-usb-gadget-uac2
View file

@ -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)

1
Documentation/usb/gadget-testing.rst
View file

@ -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)

100
drivers/usb/gadget/function/f_uac2.c
View file

@ -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,
};
@ -649,7 +650,9 @@ static void setup_headers(struct f_uac2_opts *opts,
headers[i++] = USBDHDR(epout_desc_comp);
headers[i++] = USBDHDR(&as_iso_out_desc);
headers[i++] = USBDHDR(epin_fback_desc);
if (EPOUT_FBACK_IN_EN(opts))
headers[i++] = USBDHDR(epin_fback_desc);
}
if (EPIN_EN(opts)) {
headers[i++] = USBDHDR(&std_as_in_if0_desc);
@ -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)) {
@ -883,11 +903,14 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
return -ENODEV;
}
agdev->in_ep_fback = usb_ep_autoconfig(gadget,
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__);
return -ENODEV;
if (!agdev->in_ep_fback) {
dev_err(dev, "%s:%d Error!\n",
__func__, __LINE__);
return -ENODEV;
}
}
}
@ -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;
}

2
drivers/usb/gadget/function/u_uac2.h
View file

@ -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;