linux-kernel - [PATCH 1/2] serial: omap: enable PM runtime only when its fully configured

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Date:	Fri, 12 Jul 2013 14:55:41 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	<linux-serial@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Tony Lindgren <tony@...mide.com>,
	Rajendra Nayak <rnayak@...com>, Felipe Balbi <balbi@...com>,
	Kevin Hilman <khilman@...aro.org>
Subject: [PATCH 1/2] serial: omap: enable PM runtime only when its fully configured

If earlyprintk is enabled and current UART is console port the platform
code can mark it as RPM_ACTIVE to sync real IP state with PM Runtime and
avoid resuming of already active device, but now, driver initialization
will be performed in the wrong way:

	pm_runtime_enable(&pdev->dev);
    <-- PM runtime alowed (device state RPM_ACTIVE)
	if (omap_up_info->autosuspend_timeout == 0)
		omap_up_info->autosuspend_timeout = -1;
	device_init_wakeup(up->dev, true);
	pm_runtime_use_autosuspend(&pdev->dev);
	<-- update_autosuspend() will be called and it will disable device
        (device state RPM_SUSPENDED)
	pm_runtime_set_autosuspend_delay(&pdev->dev,
			omap_up_info->autosuspend_timeout);
	<-- update_autosuspend() will be called which will re-enable device
        (device state RPM_ACTIVE), because autosuspend_timeout < 0

	pm_runtime_irq_safe(&pdev->dev);
	pm_runtime_get_sync(&pdev->dev);
	<-- will do nothing

Such behavior isn't expected by OMAP serial drivers and causes
unpredictable calls of serial_omap_runtime_suspend() and
serial_omap_runtime_resume().

Hence, fix it by allowing PM runtime only after all its parameters are
configured.

CC: Tony Lindgren <tony@...mide.com>
CC: Rajendra Nayak <rnayak@...com>
CC: Felipe Balbi <balbi@...com>
CC: Kevin Hilman <khilman@...aro.org>

Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
tested on OMAP4 SDP with and without earlyprintk enabled.
 drivers/tty/serial/omap-serial.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b6d1728..f39bf0c 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1501,7 +1501,6 @@ static int serial_omap_probe(struct platform_device *pdev)
 	INIT_WORK(&up->qos_work, serial_omap_uart_qos_work);
 
 	platform_set_drvdata(pdev, up);
-	pm_runtime_enable(&pdev->dev);
 	if (omap_up_info->autosuspend_timeout == 0)
 		omap_up_info->autosuspend_timeout = -1;
 	device_init_wakeup(up->dev, true);
@@ -1510,6 +1509,8 @@ static int serial_omap_probe(struct platform_device *pdev)
 			omap_up_info->autosuspend_timeout);
 
 	pm_runtime_irq_safe(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
 	pm_runtime_get_sync(&pdev->dev);
 
 	omap_serial_fill_features_erratas(up);
-- 
1.7.9.5

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