ANDROID: arm: add option to flush console before reboot

If the console_lock was held while the system was rebooted, the messages
in the temporary logbuffer would not have propogated to all the console
drivers.

This force releases the console lock if it failed to be acquired.

Change-Id: I193dcf7b968be17966833e50b8b8bc70d5d9fe89
Signed-off-by: Dima Zavin <dima@android.com>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 63a36f0a8306057647b6ae73b05e64dd44e861a2..858638134bfa79a6f47f6c3b02d1f7ca0214d564 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1826,6 +1826,15 @@ config XEN
        help
          Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
 
+config ARM_FLUSH_CONSOLE_ON_RESTART
+       bool "Force flush the console on restart"
+       help
+         If the console is locked while the system is rebooted, the messages
+         in the temporary logbuffer would not have propogated to all the
+         console drivers. This option forces the console lock to be
+         released if it failed to be acquired, which will cause all the
+         pending messages to be flushed.
+
 endmenu
 
 menu "Boot options"

diff --git a/arch/arm/kernel/reboot.c b/arch/arm/kernel/reboot.c
index 3b2aa9a9fe268d45335f781c4aa22cf573753a1b..c74249136f18d732d8f548eaf58f423365ae2be3 100644 (file)
--- a/arch/arm/kernel/reboot.c
+++ b/arch/arm/kernel/reboot.c
@@ -6,6 +6,7 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/delay.h>
 #include <linux/reboot.h>
@@ -125,6 +126,31 @@ void machine_power_off(void)
                pm_power_off();
 }
 
+#ifdef CONFIG_ARM_FLUSH_CONSOLE_ON_RESTART
+void arm_machine_flush_console(void)
+{
+       printk("\n");
+       pr_emerg("Restarting %s\n", linux_banner);
+       if (console_trylock()) {
+               console_unlock();
+               return;
+       }
+
+       mdelay(50);
+
+       local_irq_disable();
+       if (!console_trylock())
+               pr_emerg("arm_restart: Console was locked! Busting\n");
+       else
+               pr_emerg("arm_restart: Console was locked!\n");
+       console_unlock();
+}
+#else
+void arm_machine_flush_console(void)
+{
+}
+#endif
+
 /*
  * Restart requires that the secondary CPUs stop performing any activity
  * while the primary CPU resets the system. Systems with a single CPU can
@@ -141,6 +167,10 @@ void machine_restart(char *cmd)
        local_irq_disable();
        smp_send_stop();
 
+       /* Flush the console to make sure all the relevant messages make it
+        * out to the console drivers */
+       arm_machine_flush_console();
+
        if (arm_pm_restart)
                arm_pm_restart(reboot_mode, cmd);
        else