From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neeraj Upadhyay Subject: [PATCH] tty: serial: msm: Move request_irq to the end of startup Date: Mon, 7 Aug 2017 11:51:25 +0530 Message-ID: <1502086885-8390-1-git-send-email-neeraju@codeaurora.org> Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:52466 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751564AbdHGGVv (ORCPT ); Mon, 7 Aug 2017 02:21:51 -0400 Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: andy.gross@linaro.org, david.brown@linaro.org, gregkh@linuxfoundation.org, jslaby@suse.com Cc: sboyd@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org, linux-serial@vger.kernel.org, sramana@codeaurora.org, Neeraj Upadhyay Move the request_irq() call to the end of the msm_startup(), so that we don't handle interrupts while msm_startup() is running. This avoids potential races while initialization is in progress. For example, consider below scenario where rx handler reads the intermediate value of dma->chan, set in msm_request_rx_dma(), and tries to do dma mapping, which results in data abort. uart_port_startup() msm_startup() request_irq() ... msm_request_rx_dma() ... dma->chan = dma_request_slave_channel_reason(dev, "rx"); msm_uart_irq() msm_handle_rx_dm() msm_start_rx_dma() dma->desc = dma_map_single() Signed-off-by: Neeraj Upadhyay --- drivers/tty/serial/msm_serial.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 6788e75..1db79ee 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -1175,11 +1175,6 @@ static int msm_startup(struct uart_port *port) snprintf(msm_port->name, sizeof(msm_port->name), "msm_serial%d", port->line); - ret = request_irq(port->irq, msm_uart_irq, IRQF_TRIGGER_HIGH, - msm_port->name, port); - if (unlikely(ret)) - return ret; - msm_init_clock(port); if (likely(port->fifosize > 12)) @@ -1206,7 +1201,21 @@ static int msm_startup(struct uart_port *port) msm_request_rx_dma(msm_port, msm_port->uart.mapbase); } + ret = request_irq(port->irq, msm_uart_irq, IRQF_TRIGGER_HIGH, + msm_port->name, port); + if (unlikely(ret)) + goto err_irq; + return 0; + +err_irq: + if (msm_port->is_uartdm) + msm_release_dma(msm_port); + + clk_disable_unprepare(msm_port->pclk); + clk_disable_unprepare(msm_port->clk); + + return ret; } static void msm_shutdown(struct uart_port *port) -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation