[PATCH 2/2] dell: speed probing time up and reduce udev dependency

[Carlo Lobrano]

Currently Dell plugin implements a retry logic of three commands
(AT+GMI, AT+CGMI, ATI1I2I3) to detect modem's vendor string.
Moreover, since Telit modems always reply to the first command, to speed
the probing time up, those modem are tagged with an Udev rule so that we
can avoid sending the other two commands at all.

However, the retry logic is in case a port needs some time to reply, so
it makes sense to apply it only to the first command. Then if the port still
does not respond with any kind of reply, that probably means that it is not
AT capable and we can skip the other AT commands as well.

Then, this patch:
- sets a maximum number of timeouts for AT+GMI to 3. After this
  timeouts, the port is considered not AT-capable.
- sets AT+CGMI and ATI1I2I3 to be sent only once.
- removes Dell udev rule for tagging Telit Modems.
---

Updated the patch according to Aleksander code review.

---
 plugins/dell/77-mm-dell-port-types.rules |  4 ----
 plugins/dell/mm-plugin-dell.c            | 26 ++++++++++++++++----------
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/plugins/dell/77-mm-dell-port-types.rules b/plugins/dell/77-mm-dell-port-types.rules
index bbb59b9..206fb6e 100644
--- a/plugins/dell/77-mm-dell-port-types.rules
+++ b/plugins/dell/77-mm-dell-port-types.rules
@@ -8,9 +8,5 @@ GOTO="mm_dell_port_types_end"
 LABEL="mm_dell_vendorcheck"
 SUBSYSTEMS=="usb", ATTRS{bInterfaceNumber}=="?*", ENV{.MM_USBIFNUM}="$attr{bInterfaceNumber}"
 
-# DW5580 is a Dell-branded Telit modem
-# tag is needed here for dynamic port recognition
-ATTRS{idVendor}=="413c", ATTRS{idProduct}=="81ba", ENV{ID_MM_TELIT_PORTS_TAGGED}="1"
-
 GOTO="mm_dell_port_types_end"
 LABEL="mm_dell_port_types_end"
diff --git a/plugins/dell/mm-plugin-dell.c b/plugins/dell/mm-plugin-dell.c
index f9dfd1a..f982cfb 100644
--- a/plugins/dell/mm-plugin-dell.c
+++ b/plugins/dell/mm-plugin-dell.c
@@ -45,6 +45,8 @@
 #include "mm-broadband-modem-mbim.h"
 #endif
 
+#define MAX_PORT_PROBE_TIMEOUTS 3
+
 G_DEFINE_TYPE (MMPluginDell, mm_plugin_dell, MM_TYPE_PLUGIN)
 
 MM_PLUGIN_DEFINE_MAJOR_VERSION
@@ -70,6 +72,7 @@ typedef struct {
     guint gmi_retries;
     guint cgmi_retries;
     guint ati_retries;
+    guint timeouts;
 } CustomInitContext;
 
 static void
@@ -140,6 +143,8 @@ static void custom_init_step (CustomInitContext *ctx);
 static void
 custom_init_step_next_command (CustomInitContext *ctx)
 {
+    ctx->timeouts = 0;
+
     if (ctx->gmi_retries > 0)
         ctx->gmi_retries = 0;
     else if (ctx->cgmi_retries > 0)
@@ -169,6 +174,7 @@ response_ready (MMPortSerialAt *port,
             return;
         }
         /* Directly retry same command on timeout */
+        ctx->timeouts++;
         custom_init_step (ctx);
         g_error_free (error);
         return;
@@ -269,6 +275,12 @@ custom_init_step (CustomInitContext *ctx)
     }
 #endif
 
+    if (ctx->timeouts >= MAX_PORT_PROBE_TIMEOUTS) {
+        mm_dbg ("(Dell) couldn't flip secondary port to AT in (%s): too many timeouts",
+                mm_port_get_device (MM_PORT (ctx->port)));
+        goto out;
+    }
+
     if (ctx->gmi_retries > 0) {
         ctx->gmi_retries--;
         mm_port_serial_at_command (ctx->port,
@@ -309,9 +321,10 @@ custom_init_step (CustomInitContext *ctx)
         return;
     }
 
-    /* Finish custom_init */
     mm_dbg ("(Dell) couldn't flip secondary port to AT in (%s): all retries consumed",
             mm_port_get_device (MM_PORT (ctx->port)));
+out:
+    /* Finish custom_init */
     g_simple_async_result_set_op_res_gboolean (ctx->result, TRUE);
     custom_init_context_complete_and_free (ctx);
 }
@@ -337,15 +350,8 @@ dell_custom_init (MMPortProbe *probe,
     ctx->port = g_object_ref (port);
     ctx->cancellable = cancellable ? g_object_ref (cancellable) : NULL;
     ctx->gmi_retries = 3;
-    ctx->cgmi_retries = 3;
-    ctx->ati_retries = 3;
-
-    /* Dell-branded Telit modems always answer to +GMI
-     * Avoid +CGMI and ATI sending for minimizing port probing time */
-    if (mm_kernel_device_get_global_property_as_boolean (port_device, "ID_MM_TELIT_PORTS_TAGGED")) {
-        ctx->cgmi_retries = 0;
-        ctx->ati_retries = 0;
-    }
+    ctx->cgmi_retries = 1;
+    ctx->ati_retries = 1;
 
     custom_init_step (ctx);
 }
-- 
2.9.3