qmi-firmware-update: always validate type of TTY before using it

When listing TTYs or waiting for TTYs, always explicitly specify the
exact mode the modem should be in, so that we don't get the wrong
device.

E.g. after a reset request, always wait for a TTY with the device in
download mode.

The modem mode is automatically detected based on the amount of USB
interfaces the device exposes. If the device has a single USB
interface, then it's in download mode, otherwise it's in modem mode.
A vid:pid match could also be possible, but it would be harder to
maintain. Let's use this approach for now and see how it goes.

10 files changed, 187 insertions, 99 deletions

diff --git a/src/qmi-firmware-update/qfu-device-selection.c b/src/qmi-firmware-update/qfu-device-selection.c
index 138e813f..21e490d8 100644
--- a/src/qmi-firmware-update/qfu-device-selection.c
+++ b/src/qmi-firmware-update/qfu-device-selection.c
@@ -54,7 +54,8 @@ struct _QfuDeviceSelectionPrivate {
 
 static GFile *
 device_selection_get_single (QfuDeviceSelection   *self,
-                             QfuHelpersDeviceType  device_type)
+                             QfuHelpersDeviceType  device_type,
+                             QfuHelpersDeviceMode  device_mode)
 {
     GFile *first_selection = NULL;
     GFile *preferred_selection = NULL;
@@ -65,7 +66,7 @@ device_selection_get_single (QfuDeviceSelection   *self,
              qfu_helpers_device_type_to_string (device_type),
              self->priv->sysfs_path);
 
-    list = qfu_helpers_list_devices (device_type, self->priv->sysfs_path);
+    list = qfu_helpers_list_devices (device_type, device_mode, self->priv->sysfs_path);
     for (l = list; l; l = g_list_next (l)) {
         path = g_file_get_path (G_FILE (l->data));
         g_debug ("[qfu,device-selection]   device found: %s", path);
@@ -100,20 +101,22 @@ device_selection_get_single (QfuDeviceSelection   *self,
 GFile *
 qfu_device_selection_get_single_cdc_wdm (QfuDeviceSelection *self)
 {
-    return device_selection_get_single (self, QFU_HELPERS_DEVICE_TYPE_CDC_WDM);
+    return device_selection_get_single (self, QFU_HELPERS_DEVICE_TYPE_CDC_WDM, QFU_HELPERS_DEVICE_MODE_MODEM);
 }
 
 GFile *
-qfu_device_selection_get_single_tty (QfuDeviceSelection *self)
+qfu_device_selection_get_single_tty (QfuDeviceSelection   *self,
+                                     QfuHelpersDeviceMode  mode)
 {
-    return device_selection_get_single (self, QFU_HELPERS_DEVICE_TYPE_TTY);
+    return device_selection_get_single (self, QFU_HELPERS_DEVICE_TYPE_TTY, mode);
 }
 
 /******************************************************************************/
 
 static GList *
 device_selection_get_multiple (QfuDeviceSelection   *self,
-                               QfuHelpersDeviceType  device_type)
+                               QfuHelpersDeviceType  device_type,
+                               QfuHelpersDeviceMode  device_mode)
 {
     GFile *preferred_selection = NULL;
     GList *list, *l;
@@ -123,7 +126,7 @@ device_selection_get_multiple (QfuDeviceSelection   *self,
              qfu_helpers_device_type_to_string (device_type),
              self->priv->sysfs_path);
 
-    list = qfu_helpers_list_devices (device_type, self->priv->sysfs_path);
+    list = qfu_helpers_list_devices (device_type, device_mode, self->priv->sysfs_path);
     for (l = list; l; l = g_list_next (l)) {
         path = g_file_get_path (G_FILE (l->data));
         g_debug ("[qfu,device-selection]   device found: %s", path);
@@ -149,9 +152,10 @@ device_selection_get_multiple (QfuDeviceSelection   *self,
 }
 
 GList *
-qfu_device_selection_get_multiple_ttys (QfuDeviceSelection *self)
+qfu_device_selection_get_multiple_ttys (QfuDeviceSelection   *self,
+                                        QfuHelpersDeviceMode  mode)
 {
-    return device_selection_get_multiple (self, QFU_HELPERS_DEVICE_TYPE_TTY);
+    return device_selection_get_multiple (self, QFU_HELPERS_DEVICE_TYPE_TTY, mode);
 }
 
 /******************************************************************************/
@@ -198,6 +202,7 @@ qfu_device_selection_wait_for_cdc_wdm (QfuDeviceSelection  *self,
 
     task = g_task_new (self, cancellable, callback, user_data);
     qfu_helpers_wait_for_device (QFU_HELPERS_DEVICE_TYPE_CDC_WDM,
+                                 QFU_HELPERS_DEVICE_MODE_MODEM,
                                  self->priv->sysfs_path,
                                  self->priv->peer_port,
                                  cancellable,
@@ -207,6 +212,7 @@ qfu_device_selection_wait_for_cdc_wdm (QfuDeviceSelection  *self,
 
 void
 qfu_device_selection_wait_for_tty (QfuDeviceSelection  *self,
+                                   QfuHelpersDeviceMode mode,
                                    GCancellable        *cancellable,
                                    GAsyncReadyCallback  callback,
                                    gpointer             user_data)
@@ -215,6 +221,7 @@ qfu_device_selection_wait_for_tty (QfuDeviceSelection  *self,
 
     task = g_task_new (self, cancellable, callback, user_data);
     qfu_helpers_wait_for_device (QFU_HELPERS_DEVICE_TYPE_TTY,
+                                 mode,
                                  self->priv->sysfs_path,
                                  self->priv->peer_port,
                                  cancellable,
@@ -266,7 +273,6 @@ qfu_device_selection_new (const gchar  *preferred_cdc_wdm,
     self->priv->preferred_busnum  = preferred_busnum;
     self->priv->preferred_devnum  = preferred_devnum;
 
-
     /* Initialize sysfs path from inputs */
     if (preferred_vid || preferred_devnum)
         self->priv->sysfs_path = qfu_helpers_find_by_device_info (preferred_vid, preferred_pid, preferred_busnum, preferred_devnum, error);
diff --git a/src/qmi-firmware-update/qfu-device-selection.h b/src/qmi-firmware-update/qfu-device-selection.h
index 1f9991a9..e91a5729 100644
--- a/src/qmi-firmware-update/qfu-device-selection.h
+++ b/src/qmi-firmware-update/qfu-device-selection.h
@@ -25,6 +25,8 @@
 #include <glib-object.h>
 #include <gio/gio.h>
 
+#include "qfu-helpers.h"
+
 G_BEGIN_DECLS
 
 #define QFU_TYPE_DEVICE_SELECTION            (qfu_device_selection_get_type ())
@@ -67,9 +69,12 @@ GFile *qfu_device_selection_wait_for_cdc_wdm_finish (QfuDeviceSelection   *self,
                                                      GAsyncResult         *res,
                                                      GError              **error);
 
-GFile *qfu_device_selection_get_single_tty      (QfuDeviceSelection   *self);
-GList *qfu_device_selection_get_multiple_ttys   (QfuDeviceSelection   *self);
+GFile *qfu_device_selection_get_single_tty      (QfuDeviceSelection   *self,
+                                                 QfuHelpersDeviceMode  mode);
+GList *qfu_device_selection_get_multiple_ttys   (QfuDeviceSelection   *self,
+                                                 QfuHelpersDeviceMode  mode);
 void   qfu_device_selection_wait_for_tty        (QfuDeviceSelection   *self,
+                                                 QfuHelpersDeviceMode  mode,
                                                  GCancellable         *cancellable,
                                                  GAsyncReadyCallback   callback,
                                                  gpointer              user_data);
diff --git a/src/qmi-firmware-update/qfu-helpers-sysfs.c b/src/qmi-firmware-update/qfu-helpers-sysfs.c
index 6e8b9118..0629ec8a 100644
--- a/src/qmi-firmware-update/qfu-helpers-sysfs.c
+++ b/src/qmi-firmware-update/qfu-helpers-sysfs.c
@@ -89,13 +89,14 @@ read_sysfs_attribute_link_basename (const gchar *path,
 }
 
 static gboolean
-get_device_details (const gchar  *port_sysfs_path,
-                    gchar       **out_sysfs_path,
-                    guint16      *out_vid,
-                    guint16      *out_pid,
-                    guint        *out_busnum,
-                    guint        *out_devnum,
-                    GError      **error)
+get_device_details (const gchar           *port_sysfs_path,
+                    gchar                **out_sysfs_path,
+                    QfuHelpersDeviceMode  *out_device_mode,
+                    guint16               *out_vid,
+                    guint16               *out_pid,
+                    guint                 *out_busnum,
+                    guint                 *out_devnum,
+                    GError               **error)
 {
     g_autofree gchar *iter = NULL;
     g_autofree gchar *physdev_sysfs_path = NULL;
@@ -111,6 +112,8 @@ get_device_details (const gchar  *port_sysfs_path,
         *out_devnum = 0;
     if (out_sysfs_path)
         *out_sysfs_path = NULL;
+    if (out_device_mode)
+        *out_device_mode = QFU_HELPERS_DEVICE_MODE_UNKNOWN;
 
     iter = realpath (port_sysfs_path, NULL);
 
@@ -134,6 +137,15 @@ get_device_details (const gchar  *port_sysfs_path,
         return FALSE;
     }
 
+    if (out_device_mode) {
+        aux = read_sysfs_attribute_as_num (physdev_sysfs_path, "bNumInterfaces", 10);
+        /* QDL download mode has exactly one single USB interface */
+        if (aux == 1)
+            *out_device_mode = QFU_HELPERS_DEVICE_MODE_DOWNLOAD;
+        else if (aux > 1)
+            *out_device_mode = QFU_HELPERS_DEVICE_MODE_MODEM;
+    }
+
     if (out_vid) {
         aux = read_sysfs_attribute_as_num (physdev_sysfs_path, "idVendor", 16);
         if (aux <= G_MAXUINT16)
@@ -213,7 +225,7 @@ qfu_helpers_sysfs_find_by_file (GFile   *file,
     g_autofree gchar  *physdev_sysfs_path = NULL;
     g_autofree gchar  *found_port_sysfs_path = NULL;
     g_autofree gchar  *basename = NULL;
-    guint              i;
+    guint             i;
 
     basename = g_file_get_basename (file);
     if (!basename) {
@@ -247,7 +259,7 @@ qfu_helpers_sysfs_find_by_file (GFile   *file,
     }
 
     if (!get_device_details (found_port_sysfs_path,
-                             &physdev_sysfs_path, NULL, NULL, NULL, NULL,
+                             &physdev_sysfs_path, NULL, NULL, NULL, NULL, NULL,
                              error))
         return NULL;
 
@@ -272,12 +284,12 @@ device_already_added (GPtrArray   *ptr,
 }
 
 static GPtrArray *
-find_by_device_info_in_subsystem (GPtrArray    *sysfs_paths,
-                                  const gchar  *subsystem,
-                                  guint16       vid,
-                                  guint16       pid,
-                                  guint         busnum,
-                                  guint         devnum)
+find_by_device_info_in_subsystem (GPtrArray             *sysfs_paths,
+                                  const gchar           *subsystem,
+                                  guint16                vid,
+                                  guint16                pid,
+                                  guint                  busnum,
+                                  guint                  devnum)
 {
     g_autofree gchar           *subsys_sysfs_path = NULL;
     g_autoptr(GFile)            subsys_sysfs_file = NULL;
@@ -292,14 +304,14 @@ find_by_device_info_in_subsystem (GPtrArray    *sysfs_paths,
                                          NULL);
     if (direnum) {
         while (TRUE) {
-            GFileInfo        *info = NULL;
-            g_autoptr(GFile)  child = NULL;
-            g_autofree gchar *child_path = NULL;
-            guint16           device_vid = 0;
-            guint16           device_pid = 0;
-            guint             device_busnum = 0;
-            guint             device_devnum = 0;
-            g_autofree gchar *device_sysfs_path = NULL;
+            GFileInfo            *info = NULL;
+            g_autoptr(GFile)      child = NULL;
+            g_autofree gchar     *child_path = NULL;
+            guint16               device_vid = 0;
+            guint16               device_pid = 0;
+            guint                 device_busnum = 0;
+            guint                 device_devnum = 0;
+            g_autofree gchar     *device_sysfs_path = NULL;
 
             if (!g_file_enumerator_iterate (direnum, &info, NULL, NULL, NULL) || !info)
                 break;
@@ -308,6 +320,7 @@ find_by_device_info_in_subsystem (GPtrArray    *sysfs_paths,
             child_path = g_file_get_path (child);
             if (get_device_details (child_path,
                                     &device_sysfs_path,
+                                    NULL,
                                     &device_vid,
                                     &device_pid,
                                     &device_busnum,
@@ -383,18 +396,20 @@ qfu_helpers_sysfs_find_by_device_info (guint16   vid,
 /******************************************************************************/
 
 static GFile *
-device_matches_sysfs_and_type (GFile                *file,
-                               const gchar          *sysfs_path,
-                               QfuHelpersDeviceType  type)
+device_matches (GFile                *file,
+                QfuHelpersDeviceType  type,
+                QfuHelpersDeviceMode  mode,
+                const gchar          *sysfs_path)
 {
-    g_autofree gchar *port_sysfs_path = NULL;
-    g_autofree gchar *device_sysfs_path = NULL;
-    g_autofree gchar *device_driver = NULL;
-    g_autofree gchar *device_path = NULL;
+    g_autofree gchar     *port_sysfs_path = NULL;
+    g_autofree gchar     *device_sysfs_path = NULL;
+    g_autofree gchar     *device_driver = NULL;
+    g_autofree gchar     *device_path = NULL;
+    QfuHelpersDeviceMode  device_mode = QFU_HELPERS_DEVICE_MODE_UNKNOWN;
 
     port_sysfs_path = g_file_get_path (file);
     if (!get_device_details (port_sysfs_path,
-                             &device_sysfs_path, NULL, NULL, NULL, NULL,
+                             &device_sysfs_path, &device_mode, NULL, NULL, NULL, NULL,
                              NULL))
         return NULL;
 
@@ -404,6 +419,9 @@ device_matches_sysfs_and_type (GFile                *file,
     if (g_strcmp0 (device_sysfs_path, sysfs_path) != 0)
         return NULL;
 
+    if (device_mode != mode)
+        return NULL;
+
     if (!get_interface_details (port_sysfs_path, &device_driver, NULL))
         return NULL;
 
@@ -427,6 +445,7 @@ device_matches_sysfs_and_type (GFile                *file,
 
 GList *
 qfu_helpers_sysfs_list_devices (QfuHelpersDeviceType  device_type,
+                                QfuHelpersDeviceMode  device_mode,
                                 const gchar          *sysfs_path)
 {
     const gchar **subsys_list = NULL;
@@ -469,7 +488,7 @@ qfu_helpers_sysfs_list_devices (QfuHelpersDeviceType  device_type,
                 break;
 
             child = g_file_enumerator_get_child (direnum, info);
-            devfile = device_matches_sysfs_and_type (child, sysfs_path, device_type);
+            devfile = device_matches (child, device_type, device_mode, sysfs_path);
             if (devfile)
                 files = g_list_prepend (files, g_steal_pointer (&devfile));
         }
@@ -488,6 +507,7 @@ qfu_helpers_sysfs_list_devices (QfuHelpersDeviceType  device_type,
 
 typedef struct {
     QfuHelpersDeviceType  device_type;
+    QfuHelpersDeviceMode  device_mode;
     gchar                *sysfs_path;
     gchar                *peer_port;
     guint                 check_attempts;
@@ -515,13 +535,14 @@ qfu_helpers_sysfs_wait_for_device_finish (GAsyncResult  *res,
 
 static GFile *
 wait_for_device_lookup (QfuHelpersDeviceType  device_type,
+                        QfuHelpersDeviceMode  device_mode,
                         const gchar          *sysfs_path,
                         const gchar          *peer_port)
 {
     GList *devices;
     GFile *file;
 
-    devices = qfu_helpers_sysfs_list_devices (device_type, sysfs_path);
+    devices = qfu_helpers_sysfs_list_devices (device_type, device_mode, sysfs_path);
     if (!devices) {
         g_autofree gchar *tmp = NULL;
         g_autofree gchar *path = NULL;
@@ -534,7 +555,7 @@ wait_for_device_lookup (QfuHelpersDeviceType  device_type,
         path = realpath (tmp, NULL);
         if (path) {
             g_debug ("[qfu-sysfs] peer lookup: %s => %s", peer_port, path);
-            devices = qfu_helpers_sysfs_list_devices (device_type, path);
+            devices = qfu_helpers_sysfs_list_devices (device_type, device_mode, path);
             if (!devices)
                 return NULL;
         }
@@ -561,7 +582,7 @@ wait_for_device_check (GTask *task)
     ctx = (WaitForDeviceContext *) g_task_get_task_data (task);
 
     /* Check devices matching */
-    device = wait_for_device_lookup (ctx->device_type, ctx->sysfs_path, ctx->peer_port);
+    device = wait_for_device_lookup (ctx->device_type, ctx->device_mode, ctx->sysfs_path, ctx->peer_port);
     if (!device) {
         /* No devices found */
         if (ctx->check_attempts == WAIT_FOR_DEVICE_CHECK_ATTEMPTS) {
@@ -625,18 +646,20 @@ wait_for_device_cancelled (GCancellable *cancellable,
 }
 
 void
-qfu_helpers_sysfs_wait_for_device (QfuHelpersDeviceType   device_type,
-                                   const gchar           *sysfs_path,
-                                   const gchar           *peer_port,
-                                   GCancellable          *cancellable,
-                                   GAsyncReadyCallback    callback,
-                                   gpointer               user_data)
+qfu_helpers_sysfs_wait_for_device (QfuHelpersDeviceType  device_type,
+                                   QfuHelpersDeviceMode  device_mode,
+                                   const gchar          *sysfs_path,
+                                   const gchar          *peer_port,
+                                   GCancellable         *cancellable,
+                                   GAsyncReadyCallback   callback,
+                                   gpointer              user_data)
 {
     GTask                *task;
     WaitForDeviceContext *ctx;
 
     ctx = g_slice_new0 (WaitForDeviceContext);
     ctx->device_type = device_type;
+    ctx->device_mode = device_mode;
     ctx->sysfs_path = g_strdup (sysfs_path);
     ctx->peer_port = g_strdup (peer_port);
 
diff --git a/src/qmi-firmware-update/qfu-helpers-sysfs.h b/src/qmi-firmware-update/qfu-helpers-sysfs.h
index 39790e68..3f1162da 100644
--- a/src/qmi-firmware-update/qfu-helpers-sysfs.h
+++ b/src/qmi-firmware-update/qfu-helpers-sysfs.h
@@ -30,20 +30,20 @@
 
 G_BEGIN_DECLS
 
-gchar *qfu_helpers_sysfs_find_by_file          (GFile        *file,
-                                                GError      **error);
-gchar *qfu_helpers_sysfs_find_by_file_path     (const gchar  *path,
-                                                GError      **error);
-gchar *qfu_helpers_sysfs_find_by_device_info   (guint16       vid,
-                                                guint16       pid,
-                                                guint         busnum,
-                                                guint         devnum,
-                                                GError      **error);
+gchar *qfu_helpers_sysfs_find_by_file          (GFile    *file,
+                                                GError  **error);
+gchar *qfu_helpers_sysfs_find_by_device_info   (guint16   vid,
+                                                guint16   pid,
+                                                guint     busnum,
+                                                guint     devnum,
+                                                GError  **error);
 
 GList *qfu_helpers_sysfs_list_devices           (QfuHelpersDeviceType   device_type,
+                                                 QfuHelpersDeviceMode   device_mode,
                                                  const gchar           *sysfs_path);
 
 void   qfu_helpers_sysfs_wait_for_device        (QfuHelpersDeviceType   device_type,
+                                                 QfuHelpersDeviceMode   device_mode,
                                                  const gchar           *sysfs_path,
                                                  const gchar           *peer_port,
                                                  GCancellable          *cancellable,
diff --git a/src/qmi-firmware-update/qfu-helpers-udev.c b/src/qmi-firmware-update/qfu-helpers-udev.c
index 667ce038..bda91061 100644
--- a/src/qmi-firmware-update/qfu-helpers-udev.c
+++ b/src/qmi-firmware-update/qfu-helpers-udev.c
@@ -39,13 +39,14 @@ static const gchar *tty_subsys_list[]     = { "tty", NULL };
 static const gchar *cdc_wdm_subsys_list[] = { "usbmisc", "usb", NULL };
 
 static gboolean
-udev_helper_get_udev_device_details (GUdevDevice  *device,
-                                     gchar       **out_sysfs_path,
-                                     guint16      *out_vid,
-                                     guint16      *out_pid,
-                                     guint        *out_busnum,
-                                     guint        *out_devnum,
-                                     GError      **error)
+get_device_details (GUdevDevice           *device,
+                    gchar                **out_sysfs_path,
+                    QfuHelpersDeviceMode  *out_device_mode,
+                    guint16               *out_vid,
+                    guint16               *out_pid,
+                    guint                 *out_busnum,
+                    guint                 *out_devnum,
+                    GError               **error)
 {
     GUdevDevice *parent;
     gulong       aux;
@@ -60,6 +61,8 @@ udev_helper_get_udev_device_details (GUdevDevice  *device,
         *out_busnum = 0;
     if (out_devnum)
         *out_devnum = 0;
+    if (out_device_mode)
+        *out_device_mode = QFU_HELPERS_DEVICE_MODE_UNKNOWN;
 
     /* We need to look for the parent GUdevDevice which has a "usb_device"
      * devtype. */
@@ -85,6 +88,15 @@ udev_helper_get_udev_device_details (GUdevDevice  *device,
     if (out_sysfs_path)
         *out_sysfs_path = g_strdup (g_udev_device_get_sysfs_path (parent));
 
+    if (out_device_mode) {
+        aux = strtoul (g_udev_device_get_sysfs_attr (parent, "bNumInterfaces"), NULL, 10);
+        /* QDL download mode has exactly one single USB interface */
+        if (aux == 1)
+            *out_device_mode = QFU_HELPERS_DEVICE_MODE_DOWNLOAD;
+        else if (aux > 1)
+            *out_device_mode = QFU_HELPERS_DEVICE_MODE_MODEM;
+    }
+
     if (out_vid) {
         aux = strtoul (g_udev_device_get_property (parent, "ID_VENDOR_ID"), NULL, 16);
         if (aux <= G_MAXUINT16)
@@ -186,9 +198,9 @@ qfu_helpers_udev_find_by_file (GFile   *file,
         goto out;
     }
 
-    if (!udev_helper_get_udev_device_details (device,
-                                              &sysfs_path, NULL, NULL, NULL, NULL,
-                                              error))
+    if (!get_device_details (device,
+                             &sysfs_path, NULL, NULL, NULL, NULL, NULL,
+                             error))
         goto out;
 
     g_debug ("[qfu-udev] sysfs path for '%s' found: %s", basename, sysfs_path);
@@ -239,13 +251,14 @@ udev_helper_find_by_device_info_in_subsystem (GPtrArray    *sysfs_paths,
 
         device = G_UDEV_DEVICE (iter->data);
 
-        if (udev_helper_get_udev_device_details (device,
-                                                 &device_sysfs_path,
-                                                 &device_vid,
-                                                 &device_pid,
-                                                 &device_busnum,
-                                                 &device_devnum,
-                                                 NULL)) {
+        if (get_device_details (device,
+                                &device_sysfs_path,
+                                NULL,
+                                &device_vid,
+                                &device_pid,
+                                &device_busnum,
+                                &device_devnum,
+                                NULL)) {
             if ((vid == 0 || vid == device_vid) &&
                 (pid == 0 || pid == device_pid) &&
                 (busnum == 0 || busnum == device_busnum) &&
@@ -332,18 +345,20 @@ out:
 /******************************************************************************/
 
 static GFile *
-device_matches_sysfs_and_type (GUdevDevice          *device,
-                               const gchar          *sysfs_path,
-                               QfuHelpersDeviceType  type)
+device_matches (GUdevDevice          *device,
+                QfuHelpersDeviceType  type,
+                QfuHelpersDeviceMode  mode,
+                const gchar          *sysfs_path)
 {
-    GFile *file = NULL;
-    gchar *device_sysfs_path = NULL;
-    gchar *device_driver = NULL;
-    gchar *device_path = NULL;
-
-    if (!udev_helper_get_udev_device_details (device,
-                                              &device_sysfs_path, NULL, NULL, NULL, NULL,
-                                              NULL))
+    GFile                *file = NULL;
+    gchar                *device_sysfs_path = NULL;
+    gchar                *device_driver = NULL;
+    gchar                *device_path = NULL;
+    QfuHelpersDeviceMode  device_mode = QFU_HELPERS_DEVICE_MODE_UNKNOWN;
+
+    if (!get_device_details (device,
+                             &device_sysfs_path, &device_mode, NULL, NULL, NULL, NULL,
+                             NULL))
         goto out;
 
     if (!device_sysfs_path)
@@ -352,6 +367,9 @@ device_matches_sysfs_and_type (GUdevDevice          *device,
     if (g_strcmp0 (device_sysfs_path, sysfs_path) != 0)
         goto out;
 
+    if (device_mode != mode)
+        return NULL;
+
     if (!udev_helper_get_udev_interface_details (device,
                                                  &device_driver,
                                                  NULL))
@@ -383,6 +401,7 @@ out:
 
 GList *
 qfu_helpers_udev_list_devices (QfuHelpersDeviceType  device_type,
+                               QfuHelpersDeviceMode  device_mode,
                                const gchar          *sysfs_path)
 {
     GUdevClient  *udev;
@@ -411,7 +430,7 @@ qfu_helpers_udev_list_devices (QfuHelpersDeviceType  device_type,
         for (iter = devices; iter; iter = g_list_next (iter)) {
             GFile *file;
 
-            file = device_matches_sysfs_and_type (G_UDEV_DEVICE (iter->data), sysfs_path, device_type);
+            file = device_matches (G_UDEV_DEVICE (iter->data), device_type, device_mode, sysfs_path);
             if (file)
                 files = g_list_prepend (files, file);
             g_object_unref (G_OBJECT (iter->data));
@@ -429,6 +448,7 @@ qfu_helpers_udev_list_devices (QfuHelpersDeviceType  device_type,
 
 typedef struct {
     QfuHelpersDeviceType  device_type;
+    QfuHelpersDeviceMode  device_mode;
     GUdevClient          *udev;
     gchar                *sysfs_path;
     gchar                *peer_port;
@@ -471,7 +491,7 @@ handle_uevent (GUdevClient *client,
     if (!g_str_equal (action, "add") && !g_str_equal (action, "move") && !g_str_equal (action, "change"))
         return;
 
-    file = device_matches_sysfs_and_type (device, ctx->sysfs_path, ctx->device_type);
+    file = device_matches (device, ctx->device_type, ctx->device_mode, ctx->sysfs_path);
     if (!file && ctx->peer_port) {
         gchar *tmp, *path;
 
@@ -481,7 +501,7 @@ handle_uevent (GUdevClient *client,
         if (!path)
             return;
 
-        file = device_matches_sysfs_and_type (device, path, ctx->device_type);
+        file = device_matches (device, ctx->device_type, ctx->device_mode, path);
         g_debug ("[qfu-udev] peer lookup for %s: %s => %s",  g_udev_device_get_name (device), ctx->peer_port, path);
         g_free (path);
     }
@@ -555,6 +575,7 @@ wait_for_device_cancelled (GCancellable *cancellable,
 
 void
 qfu_helpers_udev_wait_for_device (QfuHelpersDeviceType  device_type,
+                                  QfuHelpersDeviceMode  device_mode,
                                   const gchar          *sysfs_path,
                                   const gchar          *peer_port,
                                   GCancellable         *cancellable,
@@ -566,6 +587,7 @@ qfu_helpers_udev_wait_for_device (QfuHelpersDeviceType  device_type,
 
     ctx = g_slice_new0 (WaitForDeviceContext);
     ctx->device_type = device_type;
+    ctx->device_mode = device_mode;
     ctx->sysfs_path = g_strdup (sysfs_path);
     ctx->peer_port = g_strdup (peer_port);
 
diff --git a/src/qmi-firmware-update/qfu-helpers-udev.h b/src/qmi-firmware-update/qfu-helpers-udev.h
index 9ee7d0ff..020e152d 100644
--- a/src/qmi-firmware-update/qfu-helpers-udev.h
+++ b/src/qmi-firmware-update/qfu-helpers-udev.h
@@ -42,9 +42,11 @@ gchar *qfu_helpers_udev_find_by_device_info   (guint16       vid,
                                                GError      **error);
 
 GList *qfu_helpers_udev_list_devices           (QfuHelpersDeviceType   device_type,
+                                                QfuHelpersDeviceMode   device_mode,
                                                 const gchar           *sysfs_path);
 
 void   qfu_helpers_udev_wait_for_device        (QfuHelpersDeviceType   device_type,
+                                                QfuHelpersDeviceMode   device_mode,
                                                 const gchar           *sysfs_path,
                                                 const gchar           *peer_port,
                                                 GCancellable          *cancellable,
diff --git a/src/qmi-firmware-update/qfu-helpers.c b/src/qmi-firmware-update/qfu-helpers.c
index 2ed15dca..2af69b02 100644
--- a/src/qmi-firmware-update/qfu-helpers.c
+++ b/src/qmi-firmware-update/qfu-helpers.c
@@ -40,6 +40,22 @@ qfu_helpers_device_type_to_string (QfuHelpersDeviceType type)
 
 /******************************************************************************/
 
+static const gchar *device_mode_str[] = {
+    [QFU_HELPERS_DEVICE_MODE_UNKNOWN]  = "unknown",
+    [QFU_HELPERS_DEVICE_MODE_MODEM]    = "modem",
+    [QFU_HELPERS_DEVICE_MODE_DOWNLOAD] = "download",
+};
+
+G_STATIC_ASSERT (G_N_ELEMENTS (device_mode_str) == QFU_HELPERS_DEVICE_MODE_LAST);
+
+const gchar *
+qfu_helpers_device_mode_to_string (QfuHelpersDeviceMode mode)
+{
+    return device_mode_str[mode];
+}
+
+/******************************************************************************/
+
 gchar *
 qfu_helpers_find_by_file_path (const gchar  *path,
                                GError      **error)
diff --git a/src/qmi-firmware-update/qfu-helpers.h b/src/qmi-firmware-update/qfu-helpers.h
index 5a25a37c..4df73f29 100644
--- a/src/qmi-firmware-update/qfu-helpers.h
+++ b/src/qmi-firmware-update/qfu-helpers.h
@@ -28,6 +28,8 @@
 
 G_BEGIN_DECLS
 
+/******************************************************************************/
+
 typedef enum {
     QFU_HELPERS_DEVICE_TYPE_TTY,
     QFU_HELPERS_DEVICE_TYPE_CDC_WDM,
@@ -38,6 +40,17 @@ const gchar *qfu_helpers_device_type_to_string (QfuHelpersDeviceType type);
 
 /******************************************************************************/
 
+typedef enum {
+    QFU_HELPERS_DEVICE_MODE_UNKNOWN,
+    QFU_HELPERS_DEVICE_MODE_MODEM,
+    QFU_HELPERS_DEVICE_MODE_DOWNLOAD,
+    QFU_HELPERS_DEVICE_MODE_LAST
+} QfuHelpersDeviceMode;
+
+const gchar *qfu_helpers_device_mode_to_string (QfuHelpersDeviceMode mode);
+
+/******************************************************************************/
+
 gchar *qfu_helpers_find_by_file_path (const gchar  *path,
                                       GError      **error);
 gchar *qfu_helpers_find_peer_port    (const gchar  *sysfs_path,
diff --git a/src/qmi-firmware-update/qfu-reseter.c b/src/qmi-firmware-update/qfu-reseter.c
index 979294a3..3bd5dcc5 100644
--- a/src/qmi-firmware-update/qfu-reseter.c
+++ b/src/qmi-firmware-update/qfu-reseter.c
@@ -360,7 +360,7 @@ qfu_reseter_run (QfuReseter          *self,
     /* List devices to use */
     if (!self->priv->qmi_client)
         ctx->cdc_wdm = qfu_device_selection_get_single_cdc_wdm (self->priv->device_selection);
-    ctx->ttys = qfu_device_selection_get_multiple_ttys  (self->priv->device_selection);
+    ctx->ttys = qfu_device_selection_get_multiple_ttys (self->priv->device_selection, QFU_HELPERS_DEVICE_MODE_MODEM);
 
     if (!ctx->ttys && !ctx->cdc_wdm && !self->priv->qmi_client) {
         g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
diff --git a/src/qmi-firmware-update/qfu-updater.c b/src/qmi-firmware-update/qfu-updater.c
index 15d85ad3..f860c1b0 100644
--- a/src/qmi-firmware-update/qfu-updater.c
+++ b/src/qmi-firmware-update/qfu-updater.c
@@ -876,14 +876,14 @@ wait_for_tty_ready (QfuDeviceSelection *device_selection,
     g_assert (!ctx->serial_file);
     ctx->serial_file = qfu_device_selection_wait_for_tty_finish (device_selection, res, &error);
     if (!ctx->serial_file) {
-        g_prefix_error (&error, "error waiting for TTY: ");
+        g_prefix_error (&error, "error waiting for serial device in download mode: ");
         g_task_return_error (task, error);
         g_object_unref (task);
         return;
     }
 
     path = g_file_get_path (ctx->serial_file);
-    g_debug ("[qfu-updater] TTY device found: %s", path);
+    g_debug ("[qfu-updater] serial device in download mode found: %s", path);
     g_free (path);
 
     g_print ("download mode detected\n");
@@ -901,8 +901,9 @@ run_context_step_wait_for_tty (GTask *task)
 
     g_print ("rebooting in download mode...\n");
 
-    g_debug ("[qfu-updater] reset requested, now waiting for TTY device...");
+    g_debug ("[qfu-updater] reset requested, now waiting for serial device...");
     qfu_device_selection_wait_for_tty (self->priv->device_selection,
+                                       QFU_HELPERS_DEVICE_MODE_DOWNLOAD,
                                        g_task_get_cancellable (task),
                                        (GAsyncReadyCallback) wait_for_tty_ready,
                                        task);
@@ -1530,10 +1531,10 @@ qfu_updater_run (QfuUpdater          *self,
         break;
     case UPDATER_TYPE_DOWNLOAD:
         ctx->step = RUN_CONTEXT_STEP_SELECT_DEVICE;
-        ctx->serial_file = qfu_device_selection_get_single_tty (self->priv->device_selection);
+        ctx->serial_file = qfu_device_selection_get_single_tty (self->priv->device_selection, QFU_HELPERS_DEVICE_MODE_DOWNLOAD);
         if (!ctx->serial_file) {
             g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
-                                     "No serial device found to run QDL update operation");
+                                     "No serial device in download mode found to run QDL update operation");
             g_object_unref (task);
             return;
         }