add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/usb/core/endpoint.c
..
..
@@ -84,40 +84,13 @@
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 			     char *buf)
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 {
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 	struct ep_device *ep = to_ep_device(dev);
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+	unsigned int interval;
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 	char unit;
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-	unsigned interval = 0;
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-	unsigned in;
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-	in = (ep->desc->bEndpointAddress & USB_DIR_IN);
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-
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-	switch (usb_endpoint_type(ep->desc)) {
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-	case USB_ENDPOINT_XFER_CONTROL:
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-		if (ep->udev->speed == USB_SPEED_HIGH)
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-			/* uframes per NAK */
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-			interval = ep->desc->bInterval;
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-		break;
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-
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-	case USB_ENDPOINT_XFER_ISOC:
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-		interval = 1 << (ep->desc->bInterval - 1);
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-		break;
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-
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-	case USB_ENDPOINT_XFER_BULK:
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-		if (ep->udev->speed == USB_SPEED_HIGH && !in)
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-			/* uframes per NAK */
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-			interval = ep->desc->bInterval;
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-		break;
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-
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-	case USB_ENDPOINT_XFER_INT:
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-		if (ep->udev->speed == USB_SPEED_HIGH)
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-			interval = 1 << (ep->desc->bInterval - 1);
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-		else
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-			interval = ep->desc->bInterval;
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-		break;
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-	}
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-	interval *= (ep->udev->speed == USB_SPEED_HIGH) ? 125 : 1000;
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-	if (interval % 1000)
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+	interval = usb_decode_interval(ep->desc, ep->udev->speed);
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+	if (interval % 1000) {
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 		unit = 'u';
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-	else {
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+	} else {
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 		unit = 'm';
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 		interval /= 1000;
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 	}