broadband-modem-mbim: fix signal quality reporting with MBIMEx v2.0

When we enable MBIMEx v2.0, the "Signal State" responses and
indications no longer report a valid RSSI value; and instead, they
report per access technology RSRP/RSRQ values.

  >>>>>> Header:
  >>>>>>   length      = 116
  >>>>>>   type        = indicate-status (0x80000007)
  >>>>>>   transaction = 0
  >>>>>> Fragment header:
  >>>>>>   total   = 1
  >>>>>>   current = 0
  >>>>>> Contents:
  >>>>>>   service = 'basic-connect' (a289cc33-bcbb-8b4f-b6b0-133ec2aae6df)
  >>>>>>   cid     = 'signal-state' (0x0000000b)
  >>>>>> Fields:
  >>>>>>   Rssi = '99'
  >>>>>>   ErrorRate = '99'
  >>>>>>   SignalStrengthInterval = '5'
  >>>>>>   RssiThreshold = '2'
  >>>>>>   ErrorRateThreshold = '4294967295'
  >>>>>>   RsrpSnr = '{
  >>>>>>     [0] = {
  >>>>>>           Rsrp = '0'
  >>>>>>           Snr = '0'
  >>>>>>           RsrpThreshold = '4294967295'
  >>>>>>           SnrThreshold = '4294967295'
  >>>>>>           SystemType = '5g-nsa'
  >>>>>>     },
  >>>>>>     [1] = {
  >>>>>>           Rsrp = '49'
  >>>>>>           Snr = '45'
  >>>>>>           RsrpThreshold = '4294967295'
  >>>>>>           SnrThreshold = '4294967295'
  >>>>>>           SystemType = 'lte'
  >>>>>>     },
  >>>>>>   }'

4 files changed, 73 insertions, 18 deletions

diff --git a/src/mm-broadband-modem-mbim.c b/src/mm-broadband-modem-mbim.c
index 218cf597..901a4985 100644
--- a/src/mm-broadband-modem-mbim.c
+++ b/src/mm-broadband-modem-mbim.c
@@ -1698,10 +1698,13 @@ signal_state_query_ready (MbimDevice   *device,
                           GAsyncResult *res,
                           GTask        *task)
 {
-    g_autoptr(MbimMessage)  response = NULL;
-    MMBroadbandModemMbim   *self;
-    GError                 *error = NULL;
-    guint32                 rssi;
+    MMBroadbandModemMbim            *self;
+    GError                          *error = NULL;
+    g_autoptr(MbimMessage)           response = NULL;
+    g_autoptr(MbimRsrpSnrInfoArray)  rsrp_snr = NULL;
+    guint32                          rsrp_snr_count = 0;
+    guint32                          rssi;
+    guint                            quality;
 
     self = g_task_get_source_object (task);
 
@@ -1720,8 +1723,8 @@ signal_state_query_ready (MbimDevice   *device,
                 NULL, /* signal_strength_interval */
                 NULL, /* rssi_threshold */
                 NULL, /* error_rate_threshold */
-                NULL, /* rsrp_snr_count */
-                NULL, /* rsrp_snr */
+                &rsrp_snr_count,
+                &rsrp_snr,
                 &error))
             g_prefix_error (&error, "Failed processing MBIMEx v2.0 signal state response: ");
         else
@@ -1742,10 +1745,10 @@ signal_state_query_ready (MbimDevice   *device,
 
     if (error)
         g_task_return_error (task, error);
-    else
-        /* Normalize the quality. 99 means unknown, we default it to 0 */
-        g_task_return_int (task, MM_CLAMP_HIGH (rssi == 99 ? 0 : rssi, 31) * 100 / 31);
-
+    else {
+        quality = mm_signal_quality_from_mbim_signal_state (rssi, rsrp_snr, rsrp_snr_count, self);
+        g_task_return_int (task, quality);
+    }
     g_object_unref (task);
 }
 
@@ -3250,9 +3253,11 @@ basic_connect_notification_signal_state (MMBroadbandModemMbim *self,
                                          MbimDevice           *device,
                                          MbimMessage          *notification)
 {
-    g_autoptr(GError) error = NULL;
-    guint32           rssi;
-    guint32           quality;
+    g_autoptr(GError)               error = NULL;
+    g_autoptr(MbimRsrpSnrInfoArray) rsrp_snr = NULL;
+    guint32                         rsrp_snr_count = 0;
+    guint32                         rssi;
+    guint32                         quality;
 
     if (mbim_device_check_ms_mbimex_version (device, 2, 0)) {
         if (!mbim_message_ms_basic_connect_v2_signal_state_notification_parse (
@@ -3262,8 +3267,8 @@ basic_connect_notification_signal_state (MMBroadbandModemMbim *self,
                 NULL, /* signal_strength_interval */
                 NULL, /* rssi_threshold */
                 NULL, /* error_rate_threshold */
-                NULL, /* rsrp_snr_count */
-                NULL, /* rsrp_snr */
+                &rsrp_snr_count,
+                &rsrp_snr,
                 &error)) {
             mm_obj_warn (self, "failed processing MBIMEx v2.0 signal state indication: %s", error->message);
             return;
@@ -3284,9 +3289,7 @@ basic_connect_notification_signal_state (MMBroadbandModemMbim *self,
         mm_obj_dbg (self, "proccessed signal state indication");
     }
 
-    /* Normalize the quality. 99 means unknown, we default it to 0 */
-    quality = MM_CLAMP_HIGH (rssi == 99 ? 0 : rssi, 31) * 100 / 31;
-    mm_obj_dbg (self, "signal state indication: %u --> %u%%", rssi, quality);
+    quality = mm_signal_quality_from_mbim_signal_state (rssi, rsrp_snr, rsrp_snr_count, self);
     mm_iface_modem_update_signal_quality (MM_IFACE_MODEM (self), quality);
 }
 
diff --git a/src/mm-modem-helpers-mbim.c b/src/mm-modem-helpers-mbim.c
index a1debd00..8d05227a 100644
--- a/src/mm-modem-helpers-mbim.c
+++ b/src/mm-modem-helpers-mbim.c
@@ -503,3 +503,44 @@ mm_sms_state_from_mbim_message_status (MbimSmsStatus status)
     return MM_SMS_STATE_UNKNOWN;
 }
 
+/*****************************************************************************/
+
+guint
+mm_signal_quality_from_mbim_signal_state (guint                 rssi,
+                                          MbimRsrpSnrInfoArray *rsrp_snr,
+                                          guint32               rsrp_snr_count,
+                                          gpointer              log_object)
+{
+    guint quality;
+
+    /* When MBIMEx is enabled we may get RSSI unset, but per access technology
+     * RSRP available. When more than one access technology in use (e.g. 4G+5G in
+     * 5G NSA), take the highest RSRP value reported. */
+    if (rssi == 99 && rsrp_snr && rsrp_snr_count) {
+        guint i;
+        gint  max_rsrp = G_MININT;
+
+        for (i = 0; i < rsrp_snr_count; i++) {
+            MbimRsrpSnrInfo  *info;
+
+            info = rsrp_snr[i];
+            /* scale the value to dBm */
+            if (info->rsrp < 127) {
+                gint rsrp;
+
+                rsrp = -157 + info->rsrp;
+                if (rsrp > max_rsrp)
+                    max_rsrp = rsrp;
+            }
+        }
+        quality = MM_RSRP_TO_QUALITY (max_rsrp);
+        mm_obj_dbg (log_object, "signal state update: %ddBm --> %u%%", max_rsrp, quality);
+    } else {
+        /* Normalize the quality. 99 means unknown, we default it to 0 */
+        quality = MM_CLAMP_HIGH (rssi == 99 ? 0 : rssi, 31) * 100 / 31;
+        mm_obj_dbg (log_object, "signal state update: %u --> %u%%", rssi, quality);
+    }
+
+    return quality;
+}
+
diff --git a/src/mm-modem-helpers-mbim.h b/src/mm-modem-helpers-mbim.h
index 35ee98f1..3a06d03e 100644
--- a/src/mm-modem-helpers-mbim.h
+++ b/src/mm-modem-helpers-mbim.h
@@ -60,4 +60,11 @@ MbimContextType     mm_bearer_apn_type_to_mbim_context_type        (MMBearerApnT
 
 MMSmsState mm_sms_state_from_mbim_message_status (MbimSmsStatus status);
 
+/*****************************************************************************/
+
+guint mm_signal_quality_from_mbim_signal_state (guint                 rssi,
+                                                MbimRsrpSnrInfoArray *rsrp_snr,
+                                                guint32               rsrp_snr_count,
+                                                gpointer              log_object);
+
 #endif  /* MM_MODEM_HELPERS_MBIM_H */
diff --git a/src/mm-modem-helpers.h b/src/mm-modem-helpers.h
index 7391409f..4107137c 100644
--- a/src/mm-modem-helpers.h
+++ b/src/mm-modem-helpers.h
@@ -576,6 +576,10 @@ gboolean mm_sim_parse_cpol_test_response (const gchar  *response,
 #define MM_RSSI_TO_QUALITY(rssi)                                   \
     (guint8)(100 - ((CLAMP (rssi, -113, -51) + 51) * 100 / (-113 + 51)))
 
+/* Limit the value betweeen [-110,-60] and scale it to a percentage */
+#define MM_RSRP_TO_QUALITY(rsrp)                                   \
+    (guint8)(100 - ((CLAMP (rsrp, -110, -60) + 60) * 100 / (-110 + 60)))
+
 /*****************************************************************************/
 
 /* Helper function to decode eid read from esim */