v4.19.13 snapshot.
diff --git a/sound/usb/power.c b/sound/usb/power.c
new file mode 100644
index 0000000..bd303a1
--- /dev/null
+++ b/sound/usb/power.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UAC3 Power Domain state management functions
+ */
+
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/usb/audio.h>
+#include <linux/usb/audio-v2.h>
+#include <linux/usb/audio-v3.h>
+
+#include "usbaudio.h"
+#include "helper.h"
+#include "power.h"
+
+struct snd_usb_power_domain *
+snd_usb_find_power_domain(struct usb_host_interface *ctrl_iface,
+ unsigned char id)
+{
+ struct snd_usb_power_domain *pd;
+ void *p;
+
+ pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+ if (!pd)
+ return NULL;
+
+ p = NULL;
+ while ((p = snd_usb_find_csint_desc(ctrl_iface->extra,
+ ctrl_iface->extralen,
+ p, UAC3_POWER_DOMAIN)) != NULL) {
+ struct uac3_power_domain_descriptor *pd_desc = p;
+ int i;
+
+ for (i = 0; i < pd_desc->bNrEntities; i++) {
+ if (pd_desc->baEntityID[i] == id) {
+ pd->pd_id = pd_desc->bPowerDomainID;
+ pd->pd_d1d0_rec =
+ le16_to_cpu(pd_desc->waRecoveryTime1);
+ pd->pd_d2d0_rec =
+ le16_to_cpu(pd_desc->waRecoveryTime2);
+ return pd;
+ }
+ }
+ }
+
+ kfree(pd);
+ return NULL;
+}
+
+int snd_usb_power_domain_set(struct snd_usb_audio *chip,
+ struct snd_usb_power_domain *pd,
+ unsigned char state)
+{
+ struct usb_device *dev = chip->dev;
+ unsigned char current_state;
+ int err, idx;
+
+ idx = snd_usb_ctrl_intf(chip) | (pd->pd_id << 8);
+
+ err = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0),
+ UAC2_CS_CUR,
+ USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
+ UAC3_AC_POWER_DOMAIN_CONTROL << 8, idx,
+ ¤t_state, sizeof(current_state));
+ if (err < 0) {
+ dev_err(&dev->dev, "Can't get UAC3 power state for id %d\n",
+ pd->pd_id);
+ return err;
+ }
+
+ if (current_state == state) {
+ dev_dbg(&dev->dev, "UAC3 power domain id %d already in state %d\n",
+ pd->pd_id, state);
+ return 0;
+ }
+
+ err = snd_usb_ctl_msg(chip->dev, usb_sndctrlpipe(chip->dev, 0), UAC2_CS_CUR,
+ USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
+ UAC3_AC_POWER_DOMAIN_CONTROL << 8, idx,
+ &state, sizeof(state));
+ if (err < 0) {
+ dev_err(&dev->dev, "Can't set UAC3 power state to %d for id %d\n",
+ state, pd->pd_id);
+ return err;
+ }
+
+ if (state == UAC3_PD_STATE_D0) {
+ switch (current_state) {
+ case UAC3_PD_STATE_D2:
+ udelay(pd->pd_d2d0_rec * 50);
+ break;
+ case UAC3_PD_STATE_D1:
+ udelay(pd->pd_d1d0_rec * 50);
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+
+ dev_dbg(&dev->dev, "UAC3 power domain id %d change to state %d\n",
+ pd->pd_id, state);
+
+ return 0;
+}