From 78a7dce49a0e3747e5aab9791434cb71297baf42 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Tue, 4 Jun 2019 05:12:46 +0100
Subject: [PATCH 4/5] usb-host: avoid libusb_set_configuration calls
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RH-Author: Gerd Hoffmann <kraxel@redhat.com>
Message-id: <20190604051246.11374-5-kraxel@redhat.com>
Patchwork-id: 88472
O-Subject: [RHEL-8.1.0 qemu-kvm PATCH 4/4] usb-host: avoid libusb_set_configuration calls
Bugzilla: 1719228
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>

Seems some devices become confused when we call
libusb_set_configuration().  So before calling the function check
whenever the device has multiple configurations in the first place, and
in case it hasn't (which is the case for the majority of devices) simply
skip the call as it will have no effect anyway.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20190522094702.17619-4-kraxel@redhat.com
(cherry picked from commit bfe44898848614cfcb3a269bc965afbe1f0f331c)
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 hw/usb/host-libusb.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c
index dd3ed02..587ff70 100644
--- a/hw/usb/host-libusb.c
+++ b/hw/usb/host-libusb.c
@@ -1220,19 +1220,21 @@ static void usb_host_set_address(USBHostDevice *s, int addr)
 
 static void usb_host_set_config(USBHostDevice *s, int config, USBPacket *p)
 {
-    int rc;
+    int rc = 0;
 
     trace_usb_host_set_config(s->bus_num, s->addr, config);
 
     usb_host_release_interfaces(s);
-    rc = libusb_set_configuration(s->dh, config);
-    if (rc != 0) {
-        usb_host_libusb_error("libusb_set_configuration", rc);
-        p->status = USB_RET_STALL;
-        if (rc == LIBUSB_ERROR_NO_DEVICE) {
-            usb_host_nodev(s);
+    if (s->ddesc.bNumConfigurations != 1) {
+        rc = libusb_set_configuration(s->dh, config);
+        if (rc != 0) {
+            usb_host_libusb_error("libusb_set_configuration", rc);
+            p->status = USB_RET_STALL;
+            if (rc == LIBUSB_ERROR_NO_DEVICE) {
+                usb_host_nodev(s);
+            }
+            return;
         }
-        return;
     }
     p->status = usb_host_claim_interfaces(s, config);
     if (p->status != USB_RET_SUCCESS) {
-- 
1.8.3.1