Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933001AbWJISwq (ORCPT ); Mon, 9 Oct 2006 14:52:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932995AbWJISwq (ORCPT ); Mon, 9 Oct 2006 14:52:46 -0400 Received: from gateway-1237.mvista.com ([63.81.120.158]:64644 "EHLO gateway-1237.mvista.com") by vger.kernel.org with ESMTP id S933001AbWJISwp (ORCPT ); Mon, 9 Oct 2006 14:52:45 -0400 Date: Mon, 9 Oct 2006 14:52:43 -0400 From: "George G. Davis" To: linux-kernel@vger.kernel.org Cc: Russell King Subject: [PATCH] Make sure UART is powered up when dumping MCTRL status Message-ID: <20061009185243.GL21011@mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2359 Lines: 71 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 | 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 FYI: I've posted the above to the linux-serial mailing list but have not received any additional feedback after reworking to incorporate changes recommended via that mailing list. That thread ends here: http://www.spinics.net/lists/linux-serial/msg00196.html I'm now posting this reworked version to linux-kernel to move this along. TIA for comments/feedback! -- Regards, George - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/