[PATCH V2 1/2] tty: serial: imx: add lock for registers save/restore

[PATCH V2 1/2] tty: serial: imx: add lock for registers save/restore

[Anson Huang]

In noirq suspend/resume stage with no_console_suspend enabled,
imx_uart_console_write() may be called to print out log_buf
message by printk(), so there will be race condition between
imx_uart_console_write() and imx_uart_save/restore_context(),
need to add lock to protect the registers save/restore operations.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
---
 drivers/tty/serial/imx.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 239c0fa..c15332d 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2376,8 +2376,13 @@ static int imx_uart_remove(struct platform_device *pdev)
 
 static void imx_uart_restore_context(struct imx_port *sport)
 {
-	if (!sport->context_saved)
+	unsigned long flags;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+	if (!sport->context_saved) {
+		spin_unlock_irqrestore(&sport->port.lock, flags);
 		return;
+	}
 
 	imx_uart_writel(sport, sport->saved_reg[4], UFCR);
 	imx_uart_writel(sport, sport->saved_reg[5], UESC);
@@ -2390,11 +2395,15 @@ static void imx_uart_restore_context(struct imx_port *sport)
 	imx_uart_writel(sport, sport->saved_reg[2], UCR3);
 	imx_uart_writel(sport, sport->saved_reg[3], UCR4);
 	sport->context_saved = false;
+	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 static void imx_uart_save_context(struct imx_port *sport)
 {
+	unsigned long flags;
+
 	/* Save necessary regs */
+	spin_lock_irqsave(&sport->port.lock, flags);
 	sport->saved_reg[0] = imx_uart_readl(sport, UCR1);
 	sport->saved_reg[1] = imx_uart_readl(sport, UCR2);
 	sport->saved_reg[2] = imx_uart_readl(sport, UCR3);
@@ -2406,6 +2415,7 @@ static void imx_uart_save_context(struct imx_port *sport)
 	sport->saved_reg[8] = imx_uart_readl(sport, UBMR);
 	sport->saved_reg[9] = imx_uart_readl(sport, IMX21_UTS);
 	sport->context_saved = true;
+	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
 static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)
-- 
2.7.4

[PATCH V2 2/2] tty: serial: imx: add pinctrl sleep/default mode switch for suspend

[Anson Huang]

On some i.MX SoCs' low power mode, such as i.MX7D's LPSR(low power
state retention), UART iomux settings will be lost, need to add
pinctrl sleep/default mode switch during suspend/resume to make
sure UART iomux settings are correct after resume.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
---
 drivers/tty/serial/imx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index c15332d..6ccb5c4 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -24,6 +24,7 @@
 #include <linux/serial.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/rational.h>
 #include <linux/slab.h>
 #include <linux/of.h>
@@ -2449,6 +2450,8 @@ static int imx_uart_suspend_noirq(struct device *dev)
 
 	clk_disable(sport->clk_ipg);
 
+	pinctrl_pm_select_sleep_state(dev);
+
 	return 0;
 }
 
@@ -2457,6 +2460,8 @@ static int imx_uart_resume_noirq(struct device *dev)
 	struct imx_port *sport = dev_get_drvdata(dev);
 	int ret;
 
+	pinctrl_pm_select_default_state(dev);
+
 	ret = clk_enable(sport->clk_ipg);
 	if (ret)
 		return ret;
-- 
2.7.4

Re: [PATCH V2 2/2] tty: serial: imx: add pinctrl sleep/default mode switch for suspend

[Uwe Kleine-König]

On Wed, Sep 05, 2018 at 09:24:27AM +0800, Anson Huang wrote:
> On some i.MX SoCs' low power mode, such as i.MX7D's LPSR(low power
> state retention), UART iomux settings will be lost, need to add
> pinctrl sleep/default mode switch during suspend/resume to make
> sure UART iomux settings are correct after resume.
> 
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Best regards
Uwe
-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH V2 1/2] tty: serial: imx: add lock for registers save/restore

[Uwe Kleine-König]

Hello,

On Wed, Sep 05, 2018 at 09:24:26AM +0800, Anson Huang wrote:
> In noirq suspend/resume stage with no_console_suspend enabled,
> imx_uart_console_write() may be called to print out log_buf
> message by printk(), so there will be race condition between
> imx_uart_console_write() and imx_uart_save/restore_context(),
> need to add lock to protect the registers save/restore operations.
> 
> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> ---
>  drivers/tty/serial/imx.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 239c0fa..c15332d 100644

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thanks
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |