Added 'zlp-send'

This quirk, if enabled, sets LIBUSB_TRANSFER_ADD_ZERO_PACKET flag on
each outgoing transfer, which causes libusb to terminate outgoing
transfers that a multiple of the endpoint's packet size win an
extra zero length packet.

Note, there is actually no known device that actually requires this
quirk to be set. It is added just for for completeness.

ipp-usb.8

@@ -307,6 +307,10 @@ Delay between subsequent requests\.
 \fBusb\-max\-interfaces = N\fR
 .br
 Don't use more that N USB interfaces, even if more is available\.
+.IP "\(bu" 4
+\fBzlp\-send = true | false\fR
+.br
+Terminate outgoing transfers that a multiple of the endpoint's packet size win an extra zero length packet\.
 .IP "" 0
 .P
 The DELAY parameter can be specified either as an unsigned integer (in milliseconds) or as a sequence of decimal numbers with an optional fraction and a unit suffix, such as "300ms," "0\.5s," or "2m30s\." Valid time units are "ns," "us" (or "µs"), "ms," "s," "m," and "h\."

ipp-usb.8.md

@@ -387,6 +387,10 @@ The following parameters are defined:
    * `usb-max-interfaces = N`<br>
      Don't use more that N USB interfaces, even if more is available.
 
+   * `zlp-send = true | false`<br>
+     Terminate outgoing transfers that a multiple of the endpoint's
+     packet size win an extra zero length packet.
+
 The DELAY parameter can be specified either as an unsigned integer (in
 milliseconds) or as a sequence of decimal numbers with an optional
 fraction and a unit suffix, such as "300ms," "0.5s," or "2m30s." Valid

quirks.go

@@ -44,6 +44,7 @@ const (
 	QuirkNmInitTimeout       = "init-timeout"
 	QuirkNmRequestDelay      = "request-delay"
 	QuirkNmUsbMaxInterfaces  = "usb-max-interfaces"
+	QuirkNmZlpSend           = "zlp-send"
 )
 
 // quirkParse maps quirk names into appropriate parsing methods,
@@ -58,6 +59,7 @@ var quirkParse = map[string]func(*Quirk) error{
 	QuirkNmInitTimeout:       (*Quirk).parseDuration,
 	QuirkNmRequestDelay:      (*Quirk).parseDuration,
 	QuirkNmUsbMaxInterfaces:  (*Quirk).parseUint,
+	QuirkNmZlpSend:           (*Quirk).parseBool,
 }
 
 // quirkDefaultStrings contains default values for quirks, in
@@ -72,6 +74,7 @@ var quirkDefaultStrings = map[string]string{
 	QuirkNmInitTimeout:       DevInitTimeout.String(),
 	QuirkNmRequestDelay:      "0",
 	QuirkNmUsbMaxInterfaces:  "0",
+	QuirkNmZlpSend:           "false",
 }
 
 // quirkDefault contains default values for quirks, precompiled.
@@ -344,6 +347,12 @@ func (quirks Quirks) GetUsbMaxInterfaces() uint {
 	return quirks.Get(QuirkNmUsbMaxInterfaces).Parsed.(uint)
 }
 
+// GetZlpSend returns effective "zlp-send" parameter,
+// taking the whole set into consideration.
+func (quirks Quirks) GetZlpSend() bool {
+	return quirks.Get(QuirkNmZlpSend).Parsed.(bool)
+}
+
 // QuirksSet represents collection of quirks
 type QuirksSet []*Quirks
 

quirks_test.go

@@ -135,6 +135,17 @@ func TestQuirksLookup(t *testing.T) {
 			origin: "default",
 		},
 
+		{
+			model: "Unknown Device",
+			param: QuirkNmZlpSend,
+			get: func(quirks Quirks) interface{} {
+				return quirks.GetZlpSend()
+			},
+			match:  "*",
+			value:  false,
+			origin: "default",
+		},
+
 		// Quirks for some known devices
 		{
 			model: "HP ScanJet Pro 4500 fn1",

usbio_libusb.go

@@ -789,6 +789,10 @@ func (iface *UsbInterface) Send(ctx context.Context,
 		0,
 	)
 
+	if iface.quirks.GetZlpSend() {
+		xfer.flags |= C.LIBUSB_TRANSFER_ADD_ZERO_PACKET
+	}
+
 	// Submit transfer
 	rc := C.libusb_submit_transfer(xfer)
 	if rc < 0 {