From mboxrd@z Thu Jan 1 00:00:00 1970 From: "George G. Davis" Subject: [RFC][PATCH] Make sure UART is powered up when dumping MCTRL status Date: Fri, 5 May 2006 18:15:37 -0400 Message-ID: <20060505221537.GK14872@mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from gateway-1237.mvista.com ([63.81.120.158]:15657 "EHLO gateway-1237.mvista.com") by vger.kernel.org with ESMTP id S1751795AbWEEWPk (ORCPT ); Fri, 5 May 2006 18:15:40 -0400 Content-Disposition: inline Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: rmk+serial@arm.linux.org.uk, linux-serial@vger.kernel.org Greetings, 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 --- drivers/serial/serial_core.c | 12 ++++++++++++ 1 files changed, 12 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); @@ -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); + /* * Ensure that the modem control lines are de-activated. * We probably don't need a spinlock around this, but Comments appreciated. TIA! -- Regards, George