[Spice-devel] [PATCH v2] Usbredir: Avoid compression of isochronous devices

[Snir Sheriber]

Device is considered isochronous if one of its endpoints is
defined as isochronous transfer, in that case data transfer
over the usbredir channel will not be compressed

E.g.
Camera/mic device will usually be recognised as isochronous
while storage devices won't

Signed-off-by: Snir Sheriber <ssheribe at redhat.com>
---
 src/channel-usbredir.c        |  9 +++++++++
 src/usb-device-manager-priv.h |  1 +
 src/usb-device-manager.c      | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/src/channel-usbredir.c b/src/channel-usbredir.c
index 9c71c07..0accd44 100644
--- a/src/channel-usbredir.c
+++ b/src/channel-usbredir.c
@@ -544,6 +544,11 @@ void spice_usbredir_channel_disconnect_device_async(SpiceUsbredirChannel *channe
     g_object_unref(task);
 }
 
+static SpiceUsbDevice *spice_usbredir_channel_get_spice_usb_device(SpiceUsbredirChannel *channel)
+{
+    return channel->priv->spice_device;
+}
+
 G_GNUC_INTERNAL
 libusb_device *spice_usbredir_channel_get_device(SpiceUsbredirChannel *channel)
 {
@@ -672,6 +677,10 @@ static int try_write_compress_LZ4(SpiceUsbredirChannel *channel, uint8_t *data,
         /* No server compression capability - data will not be compressed */
         return FALSE;
     }
+    if(spice_usb_device_is_isochronous(spice_usbredir_channel_get_spice_usb_device(channel))) {
+        /* Don't compress - one of the device endpoints is isochronous */
+        return FALSE;
+    }
     bound = LZ4_compressBound(count);
     if (bound == 0) {
         /* Invalid bound - data will not be compressed */
diff --git a/src/usb-device-manager-priv.h b/src/usb-device-manager-priv.h
index b6fa9c9..83884d7 100644
--- a/src/usb-device-manager-priv.h
+++ b/src/usb-device-manager-priv.h
@@ -40,6 +40,7 @@ guint8 spice_usb_device_get_busnum(const SpiceUsbDevice *device);
 guint8 spice_usb_device_get_devaddr(const SpiceUsbDevice *device);
 guint16 spice_usb_device_get_vid(const SpiceUsbDevice *device);
 guint16 spice_usb_device_get_pid(const SpiceUsbDevice *device);
+gboolean spice_usb_device_is_isochronous(const SpiceUsbDevice *device);
 
 #endif
 
diff --git a/src/usb-device-manager.c b/src/usb-device-manager.c
index 53505fa..9c39cf6 100644
--- a/src/usb-device-manager.c
+++ b/src/usb-device-manager.c
@@ -153,6 +153,7 @@ typedef struct _SpiceUsbDeviceInfo {
     guint8  devaddr;
     guint16 vid;
     guint16 pid;
+    gboolean isochronous;
 #ifdef G_OS_WIN32
     guint8  state;
 #else
@@ -2017,6 +2018,30 @@ gchar *spice_usb_device_get_description(SpiceUsbDevice *device, const gchar *for
 
 
 #ifdef USE_USBREDIR
+
+static gboolean probe_isochronous_endpoint(libusb_device *libdev) {
+    struct libusb_config_descriptor * conf_desc;
+    gboolean isoc_found = FALSE;
+    gint i,j,k;
+
+    g_return_val_if_fail(libdev != NULL, FALSE);
+    g_return_val_if_fail(!libusb_get_active_config_descriptor(libdev, &conf_desc), FALSE);
+
+    for(i = 0; !isoc_found && i < conf_desc->bNumInterfaces; i++) {
+        for(j = 0; !isoc_found && j < conf_desc->interface[i].num_altsetting; j++) {
+            for(k = 0; !isoc_found && k < conf_desc->interface[i].altsetting[j].bNumEndpoints;k++) {
+                gint attributes = conf_desc->interface[i].altsetting[j].endpoint[k].bmAttributes;
+                gint type = attributes & LIBUSB_TRANSFER_TYPE_MASK;
+                if (type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS)
+                    isoc_found = TRUE;
+            }
+        }
+    }
+
+    libusb_free_config_descriptor(conf_desc);
+    return isoc_found;
+}
+
 /*
  * SpiceUsbDeviceInfo
  */
@@ -2042,6 +2067,7 @@ static SpiceUsbDeviceInfo *spice_usb_device_new(libusb_device *libdev)
     info->vid = vid;
     info->pid = pid;
     info->ref = 1;
+    info->isochronous = probe_isochronous_endpoint(libdev);
 #ifndef G_OS_WIN32
     info->libdev = libusb_ref_device(libdev);
 #endif
@@ -2085,6 +2111,15 @@ guint16 spice_usb_device_get_pid(const SpiceUsbDevice *device)
     return info->pid;
 }
 
+gboolean spice_usb_device_is_isochronous(const SpiceUsbDevice *device)
+{
+    const SpiceUsbDeviceInfo *info = (const SpiceUsbDeviceInfo *)device;
+
+    g_return_val_if_fail(info != NULL, 0);
+
+    return info->isochronous;
+}
+
 #ifdef G_OS_WIN32
 void spice_usb_device_set_state(SpiceUsbDevice *device, guint8 state)
 {
-- 
2.5.5