On Wed, May 10, 2006 at 05:39:19PM +0100, Russell King wrote:
> On Fri, May 05, 2006 at 06:15:37PM -0400, George G. Davis wrote:
> > @@ -2068,6 +2076,10 @@ uart_configure_port(struct uart_driver *
> >
> > uart_report_port(drv, port);
> >
> > + /* Power up port for set_mctrl() */
> > + if (!uart_console(port))
> > + uart_change_pm(state, 0);
> > +
>
> If it's possible for uarts to be powered down here, wouldn't it be a
> good idea to ensure that the console is also powered up?
Apologies for the delay... Here's an update which insures all serial
ports are powered up prior to accessing device registers.
Since serial devices are powered down when not in use and some of those
devices cannot be accessed when powered down, we need to enable power
around calls to get_mcrtl() when dumping port state via uart_line_info().
This resolves hangs observed on some machines while reading serial device
registers when a port is powered off.
Signed-off-by: George G. Davis <gdavis@xxxxxxxxxx>
drivers/serial/serial_core.c | 11 +++++++++++
1 files changed, 11 insertions(+)
Index: linux-2.6/drivers/serial/serial_core.c
===================================================================
--- linux-2.6.orig/drivers/serial/serial_core.c
+++ linux-2.6/drivers/serial/serial_core.c
@@ -1652,6 +1652,7 @@ static const char *uart_type(struct uart
static int uart_line_info(char *buf, struct uart_driver *drv, int i)
{
struct uart_state *state = drv->state + i;
+ int pm_state;
struct uart_port *port = state->port;
char stat_buf[32];
unsigned int status;
@@ -1674,9 +1675,16 @@ static int uart_line_info(char *buf, str
if(capable(CAP_SYS_ADMIN))
{
+ mutex_lock(&state->mutex);
+ pm_state = state->pm_state;
+ if (pm_state)
+ uart_change_pm(state, 0);
spin_lock_irq(&port->lock);
status = port->ops->get_mctrl(port);
spin_unlock_irq(&port->lock);
+ if (pm_state)
+ uart_change_pm(state, pm_state);
+ mutex_unlock(&state->mutex);
ret += sprintf(buf + ret, " tx:%d rx:%d",
port->icount.tx, port->icount.rx);
@@ -2071,6 +2079,9 @@ uart_configure_port(struct uart_driver *
uart_report_port(drv, port);
+ /* Power up port for set_mctrl() */
+ uart_change_pm(state, 0);
+
/*
* Ensure that the modem control lines are de-activated.
* We probably don't need a spinlock around this, but
--
Regards,
George
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