Sleep right up to the timeout instead of the first half if we find ourselves polling in _usb_read

usbutils.c

@@ -2021,7 +2021,7 @@ int _usb_read(struct cgpu_info *cgpu, int ep, char *buf, size_t bufsiz, int *pro
 	struct timeval tv_start;
 #endif
 	struct timeval read_start, tv_finish;
-	unsigned int initial_timeout, half_time;
+	unsigned int initial_timeout, sleep_time;
 	double max, done;
 	int bufleft, err, got, tot;
 	__maybe_unused bool first = true;
@@ -2056,7 +2056,7 @@ int _usb_read(struct cgpu_info *cgpu, int ep, char *buf, size_t bufsiz, int *pro
 		bufleft = bufsiz;
 		err = LIBUSB_SUCCESS;
 		initial_timeout = timeout;
-		half_time = initial_timeout / 2;
+		sleep_time = initial_timeout / 2;
 		max = ((double)timeout) / 1000.0;
 		cgtime(&read_start);
 		while (bufleft > 0) {
@@ -2110,9 +2110,11 @@ int _usb_read(struct cgpu_info *cgpu, int ep, char *buf, size_t bufsiz, int *pro
 			 * if we don't sleep here, but do it only if we're not
 			 * receiving any data. */
 			timeout = initial_timeout - (done * 1000);
-			if (!got && half_time && timeout > half_time) {
-				timeout -= half_time;
-				nmsleep(half_time);
+			if (!got && sleep_time) {
+				if (timeout <= sleep_time)
+					sleep_time = timeout - 1;
+				timeout -= sleep_time;
+				nmsleep(sleep_time);
 			}
 		}
 
@@ -2131,7 +2133,7 @@ int _usb_read(struct cgpu_info *cgpu, int ep, char *buf, size_t bufsiz, int *pro
 	endlen = strlen(end);
 	err = LIBUSB_SUCCESS;
 	initial_timeout = timeout;
-	half_time = initial_timeout / 2;
+	sleep_time = initial_timeout / 2;
 	max = ((double)timeout) / 1000.0;
 	cgtime(&read_start);
 	while (bufleft > 0) {
@@ -2198,9 +2200,11 @@ int _usb_read(struct cgpu_info *cgpu, int ep, char *buf, size_t bufsiz, int *pro
 			break;
 
 		timeout = initial_timeout - (done * 1000);
-		if (!got && half_time && timeout > half_time) {
-			timeout -= half_time;
-			nmsleep(half_time);
+		if (!got && sleep_time) {
+			if (timeout <= sleep_time)
+				sleep_time = timeout - 1;
+			timeout -= sleep_time;
+			nmsleep(sleep_time);
 		}
 	}