[SERIAL] Fix Bug 4900: S3 resume oops with irattach - Thinkpad A21m

If we fail to re-startup a serial port on resume, shut it down
immediately and mark it as an error condition.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 49 insertions, 35 deletions

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 427a23858076..2331296e1e17 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -209,33 +209,45 @@ static void uart_shutdown(struct uart_state *state)
         struct uart_info *info = state->info;
         struct uart_port *port = state->port;
 
-        if (!(info->flags & UIF_INITIALIZED))
-                return;
-
         /*
-         * Turn off DTR and RTS early.
+         * Set the TTY IO error marker
          */
-        if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
-                uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
+        if (info->tty)
+                set_bit(TTY_IO_ERROR, &info->tty->flags);
 
-        /*
-         * clear delta_msr_wait queue to avoid mem leaks: we may free
-         * the irq here so the queue might never be woken up.  Note
-         * that we won't end up waiting on delta_msr_wait again since
-         * any outstanding file descriptors should be pointing at
-         * hung_up_tty_fops now.
-         */
-        wake_up_interruptible(&info->delta_msr_wait);
+        if (info->flags & UIF_INITIALIZED) {
+                info->flags &= ~UIF_INITIALIZED;
 
-        /*
-         * Free the IRQ and disable the port.
-         */
-        port->ops->shutdown(port);
+                /*
+                 * Turn off DTR and RTS early.
+                 */
+                if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
+                        uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
+
+                /*
+                 * clear delta_msr_wait queue to avoid mem leaks: we may free
+                 * the irq here so the queue might never be woken up.  Note
+                 * that we won't end up waiting on delta_msr_wait again since
+                 * any outstanding file descriptors should be pointing at
+                 * hung_up_tty_fops now.
+                 */
+                wake_up_interruptible(&info->delta_msr_wait);
+
+                /*
+                 * Free the IRQ and disable the port.
+                 */
+                port->ops->shutdown(port);
+
+                /*
+                 * Ensure that the IRQ handler isn't running on another CPU.
+                 */
+                synchronize_irq(port->irq);
+        }
 
         /*
-         * Ensure that the IRQ handler isn't running on another CPU.
+         * kill off our tasklet
          */
-        synchronize_irq(port->irq);
+        tasklet_kill(&info->tlet);
 
         /*
          * Free the transmit buffer page.
@@ -244,15 +256,6 @@ static void uart_shutdown(struct uart_state *state)
                 free_page((unsigned long)info->xmit.buf);
                 info->xmit.buf = NULL;
         }
-
-        /*
-         * kill off our tasklet
-         */
-        tasklet_kill(&info->tlet);
-        if (info->tty)
-                set_bit(TTY_IO_ERROR, &info->tty->flags);
-
-        info->flags &= ~UIF_INITIALIZED;
 }
 
 /**
@@ -1928,14 +1931,25 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
 
         if (state->info && state->info->flags & UIF_INITIALIZED) {
                 struct uart_ops *ops = port->ops;
+                int ret;
 
                 ops->set_mctrl(port, 0);
-                ops->startup(port);
-                uart_change_speed(state, NULL);
-                spin_lock_irq(&port->lock);
-                ops->set_mctrl(port, port->mctrl);
-                ops->start_tx(port);
-                spin_unlock_irq(&port->lock);
+                ret = ops->startup(port);
+                if (ret == 0) {
+                        uart_change_speed(state, NULL);
+                        spin_lock_irq(&port->lock);
+                        ops->set_mctrl(port, port->mctrl);
+                        ops->start_tx(port);
+                        spin_unlock_irq(&port->lock);
+                } else {
+                        /*
+                         * Failed to resume - maybe hardware went away?
+                         * Clear the "initialized" flag so we won't try
+                         * to call the low level drivers shutdown method.
+                         */
+                        state->info->flags &= ~UIF_INITIALIZED;
+                        uart_shutdown(state);
+                }
         }
 
         up(&state->sem);