commit bf943bce82293a304d71807081233257ff8b955b
author Freek Dijkstra <freek@macfreek.nl> Mon Jan 11 01:49:42 2021 +0100
committer Nathan Hjelm <hjelmn@google.com> Wed Jan 13 15:57:15 2021 -0700
tree de51bd713ba9f6b5411075bfa13fee799f4c6d6a
parent 073f229fd11f0d3e3098af44e59b5607aae113e2

MacOS: Silence pipe error in set_interface_alt_setting()

darwin_set_interface_altsetting() no longer returns the status of the underlying SetAlternateInterface(), but instead the result of a subsequent GetNumEndpoints() call. This reverts to the behaviour prior to commit 065e586.

Since darwin_set_interface_altsetting() resets the interface after SetAlternateInterface(), one of the consequences is that if SetAlternateInterface() returns a kIOUSBPipeStalled error, and the interface is successfully reset, darwin_set_interface_altsetting() now returns LIBUSB_SUCCESS instead of LIBUSB_ERROR_PIPE.

Closes: #838

Signed-off-by: Freek Dijkstra
Signed-off-by: Nathan Hjelm <hjelmn@google.com>

libusb/os/darwin_usb.c

diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index e415589..8055cc0 100644
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -1567,8 +1567,15 @@
     return LIBUSB_ERROR_NO_DEVICE;
 
   kresult = (*(cInterface->interface))->SetAlternateInterface (cInterface->interface, altsetting);
-  if (kresult != kIOReturnSuccess)
+  /* If a device only supports a default setting for the specified interface, then a STALL
+     (kIOUSBPipeStalled) may be returned. Ref: USB 2.0 specs 9.4.10.
+     Mimick the behaviour in e.g. the Linux kernel: in such case, reset all endpoints,
+     and hide errors.Current implementation resets the entire device, instead of single
+     interface, due to historic reasons. */
+  if (kresult != kIOReturnSuccess) {
+    usbi_warn (HANDLE_CTX (dev_handle), "SetAlternateInterface: %s", darwin_error_str(kresult));
     darwin_reset_device (dev_handle);
+  }
 
   /* update list of endpoints */
   ret = get_endpoints (dev_handle, iface);
@@ -1576,10 +1583,9 @@
     /* this should not happen */
     darwin_release_interface (dev_handle, iface);
     usbi_err (HANDLE_CTX (dev_handle), "could not build endpoint table");
-    return ret;
   }
 
-  return darwin_to_libusb (kresult);
+  return ret;
 }
 
 static int darwin_clear_halt(struct libusb_device_handle *dev_handle, unsigned char endpoint) {

libusb/version_nano.h

diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index c30b57d..ce7c73c 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11591
+#define LIBUSB_NANO 11592