[android] Optionally force an USB function on bootup. JB#41747

On some devices enumeration fails on the 1st connect after bootup unless
android usb has already been set up for some function at least once.

Add --android-bootup-function option that can be used on such devices
to force usb-moded to program some function and then clear the function
list when usb-moded is executed during device bootup.
Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

src/usb_moded-android.c

@@ -23,6 +23,7 @@
 #include <stdio.h>
 #include <glib.h>
 
+#include "usb_moded.h"
 #include "usb_moded-android.h"
 #include "usb_moded-log.h"
 #include "usb_moded-modesetting.h"
@@ -84,11 +85,17 @@ void android_init_values(void)
 {
   gchar *text;
 
+  /* If the directory is not there, no point emitting warnings
+   * about every file that is not going to be there either. */
   if( access("/sys/class/android_usb/android0", F_OK) != 0 )
   {
     goto EXIT;
   }
 
+  /* Disable */
+  write_to_file("/sys/class/android_usb/android0/enable", "0");
+
+  /* Configure */
   if( (text = get_android_serial()) )
   {
 	write_to_file("/sys/class/android_usb/android0/iSerial", text);
@@ -128,8 +135,22 @@ void android_init_values(void)
   /* For rndis to be discovered correctly in M$ Windows (vista and later) */
   write_to_file("/sys/class/android_usb/f_rndis/wceis", "1");
 
-  /* Make sure android_usb does not stay disabled in case usb moded
-   * has crashed / been killed in inconvenient time. */
+
+  /* Some devices can have enumeration issues due to incomplete
+   * configuration on the 1st connect after bootup. Briefly setting
+   * up for example mass_storage function can be utilized as a
+   * workaround in such cases. */
+  if(!init_done_p()) {
+    const char *function = get_android_bootup_function();
+    if(function) {
+      write_to_file("/sys/class/android_usb/android0/functions", function);
+      write_to_file("/sys/class/android_usb/android0/enable", "1");
+      write_to_file("/sys/class/android_usb/android0/enable", "0");
+    }
+  }
+
+  /* Clear functions and enable */
+  write_to_file("/sys/class/android_usb/android0/functions", "none");
   write_to_file("/sys/class/android_usb/android0/enable", "1");
 
 EXIT:

src/usb_moded.c

@@ -92,6 +92,30 @@ static gboolean android_ignore_next_udev_disconnect_event = FALSE;
 static gboolean systemd_notify = FALSE;
 #endif
 
+/** Optional android usb function to setup during bootup */
+static gchar *android_bootup_function = 0;
+
+
+/** Get android usb function to setup during bootup
+ *
+ * @returns function name, or NULL if no function was requested
+ */
+const char *get_android_bootup_function(void)
+{
+	return android_bootup_function;
+}
+
+/** Set android usb function to setup during bootup
+ *
+ * @param function usb function name, or NULL
+ */
+void set_android_bootup_function(const char *function)
+{
+	char *value = function ? g_strdup(function) : 0;
+	g_free(android_bootup_function);
+	android_bootup_function = value;
+}
+
 /** Default allowed cable detection delay
  *
  * To comply with USB standards, the delay should be
@@ -879,6 +903,10 @@ static void usage(void)
 		"      output version information and exit\n"
 		"  -m,  --max-cable-delay=<ms>\n"
 		"      maximum delay before accepting cable connection\n"
+		"  -b,  --android-bootup-function=<function>\n"
+		"      Setup given function during bootup. Might be required\n"
+		"      on some devices to make enumeration work on the 1st\n"
+		"      cable connect.\n"
 		"\n");
 }
 
@@ -1332,6 +1360,7 @@ int main(int argc, char* argv[])
 		{ "systemd", no_argument, 0, 'n' },
                 { "version", no_argument, 0, 'v' },
                 { "max-cable-delay", required_argument, 0, 'm' },
+                { "android-bootup-function", required_argument, 0, 'b' },
                 { 0, 0, 0, 0 }
         };
 
@@ -1343,7 +1372,7 @@ int main(int argc, char* argv[])
 	 * - - - - - - - - - - - - - - - - - - - */
 
 	 /* Parse the command-line options */
-        while ((opt = getopt_long(argc, argv, "aifsTlDdhrnvm:", options, &opt_idx)) != -1)
+        while ((opt = getopt_long(argc, argv, "aifsTlDdhrnvm:b:", options, &opt_idx)) != -1)
 	{
                 switch (opt) 
 		{
@@ -1397,6 +1426,10 @@ int main(int argc, char* argv[])
 				set_cable_connection_delay(strtol(optarg, 0, 0));
 				break;
 
+			case 'b':
+				set_android_bootup_function(optarg);
+				break;
+
 	                default:
         	                usage();
 				exit(0);
@@ -1602,6 +1635,8 @@ EXIT:
 # endif
 #endif
 
+	set_android_bootup_function(0);
+
 	/* Must be done just before exit to make sure no more wakelocks
 	 * are taken and left behind on exit path */
 	allow_suspend();

src/usb_moded.h

@@ -108,4 +108,7 @@ bool init_done_p(void);
 void set_init_done(bool reached);
 void probe_init_done(void);
 
+const char *get_android_bootup_function(void);
+void set_android_bootup_function(const char *function);
+
 #endif /* USB_MODED_H */