Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751723AbbHOEie (ORCPT ); Sat, 15 Aug 2015 00:38:34 -0400 Received: from mail-pd0-f179.google.com ([209.85.192.179]:36798 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751103AbbHOEiB (ORCPT ); Sat, 15 Aug 2015 00:38:01 -0400 From: Eduardo Valentin To: Greg Kroah-Hartman , Jiri Slaby , Fabio Estevam Cc: Sascha Hauer , Linux PM , linux-serial@vger.kernel.org, LKML , Eduardo Valentin Subject: [PATCHv4 3/4] serial: imx: add pm_qos request Date: Fri, 14 Aug 2015 21:37:47 -0700 Message-Id: <1439613468-22366-4-git-send-email-edubezval@gmail.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1439613468-22366-1-git-send-email-edubezval@gmail.com> References: <1439613468-22366-1-git-send-email-edubezval@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3785 Lines: 113 This change introduces pm_qos requests in the imx serial driver. The idea is to skip deeper C-state in case we need a strict latency requirement in the uart port. The latency is computed based on the buffer size and the current baud rate. We schedule a work queue to set the pm qos requirement. Cc: Fabio Estevam Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Eduardo Valentin --- drivers/tty/serial/imx.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index d9ccf6b..24ed0fa 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include @@ -222,6 +223,10 @@ struct imx_port { unsigned int saved_reg[10]; bool context_saved; + struct pm_qos_request pm_qos_request; + u32 latency; + u32 calc_latency; + struct work_struct qos_work; bool is_suspending; }; @@ -1320,6 +1325,14 @@ static void imx_flush_buffer(struct uart_port *port) pm_runtime_put_autosuspend(sport->port.dev); } +static void serial_imx_uart_qos_work(struct work_struct *work) +{ + struct imx_port *sport = container_of(work, struct imx_port, + qos_work); + + pm_qos_update_request(&sport->pm_qos_request, sport->latency); +} + static void imx_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) @@ -1393,6 +1406,12 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16); quot = uart_get_divisor(port, baud); + /* calculate wakeup latency constraint */ + sport->calc_latency = (USEC_PER_SEC * sport->port.fifosize) / + (baud / 8); + sport->latency = sport->calc_latency; + schedule_work(&sport->qos_work); + spin_lock_irqsave(&sport->port.lock, flags); sport->port.read_status_mask = 0; @@ -2012,6 +2031,11 @@ static int serial_imx_probe(struct platform_device *pdev) imx_ports[sport->port.line] = sport; + sport->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE; + sport->calc_latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE; + pm_qos_add_request(&sport->pm_qos_request, PM_QOS_CPU_DMA_LATENCY, + sport->latency); + INIT_WORK(&sport->qos_work, serial_imx_uart_qos_work); platform_set_drvdata(pdev, sport); device_init_wakeup(sport->port.dev, true); @@ -2041,6 +2065,7 @@ static int serial_imx_remove(struct platform_device *pdev) clk_unprepare(sport->clk_per); clk_unprepare(sport->clk_ipg); ret = uart_remove_one_port(&imx_reg, &sport->port); + pm_qos_remove_request(&sport->pm_qos_request); device_init_wakeup(&pdev->dev, false); return ret; @@ -2119,6 +2144,8 @@ static int serial_imx_runtime_suspend(struct device *dev) serial_imx_save_context(sport); serial_imx_enable_wakeup(sport, true); + sport->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE; + schedule_work(&sport->qos_work); clk_disable(sport->clk_per); clk_disable(sport->clk_ipg); @@ -2140,6 +2167,8 @@ static int serial_imx_runtime_resume(struct device *dev) } serial_imx_enable_wakeup(sport, false); + sport->latency = sport->calc_latency; + schedule_work(&sport->qos_work); serial_imx_restore_context(sport); return 0; -- 2.5.0 -- 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/