* [PATCH] tty/serial: atmel: ensure state is restored after suspending
@ 2017-02-03 22:53 Alexandre Belloni
2017-02-06 9:31 ` Nicolas Ferre
2017-02-06 11:10 ` Richard Genoud
0 siblings, 2 replies; 3+ messages in thread
From: Alexandre Belloni @ 2017-02-03 22:53 UTC (permalink / raw)
To: Richard Genoud
Cc: Greg Kroah-Hartman, Nicolas Ferre, linux-arm-kernel, linux-serial,
linux-kernel, Alexandre Belloni
When going to suspend, the UART registers may be lost because the power to
VDDcore is cut. This is not an issue in the normal case but when
no_console_suspend is used, we need to restore the registers in order to
get a functional console.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
drivers/tty/serial/atmel_serial.c | 44 +++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 168b10cad47b..22e0a73c0cb7 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -175,6 +175,17 @@ struct atmel_uart_port {
unsigned int pending_status;
spinlock_t lock_suspended;
+ struct {
+ u32 cr;
+ u32 mr;
+ u32 imr;
+ u32 brgr;
+ u32 rtor;
+ u32 ttgr;
+ u32 fmr;
+ u32 fimr;
+ } cache;
+
int (*prepare_rx)(struct uart_port *port);
int (*prepare_tx)(struct uart_port *port);
void (*schedule_rx)(struct uart_port *port);
@@ -2649,6 +2660,20 @@ static int atmel_serial_suspend(struct platform_device *pdev,
cpu_relax();
}
+ if (atmel_is_console_port(port) && !console_suspend_enabled) {
+ /* Cache register values as we won't get a full shutdown/startup
+ * cycle
+ */
+ atmel_port->cache.mr = atmel_uart_readl(port, ATMEL_US_MR);
+ atmel_port->cache.imr = atmel_uart_readl(port, ATMEL_US_IMR);
+ atmel_port->cache.brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
+ atmel_port->cache.rtor = atmel_uart_readl(port,
+ atmel_port->rtor);
+ atmel_port->cache.ttgr = atmel_uart_readl(port, ATMEL_US_TTGR);
+ atmel_port->cache.fmr = atmel_uart_readl(port, ATMEL_US_FMR);
+ atmel_port->cache.fimr = atmel_uart_readl(port, ATMEL_US_FIMR);
+ }
+
/* we can not wake up if we're running on slow clock */
atmel_port->may_wakeup = device_may_wakeup(&pdev->dev);
if (atmel_serial_clk_will_stop()) {
@@ -2671,6 +2696,25 @@ static int atmel_serial_resume(struct platform_device *pdev)
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
unsigned long flags;
+ if (atmel_is_console_port(port) && !console_suspend_enabled) {
+ atmel_uart_writel(port, ATMEL_US_MR, atmel_port->cache.mr);
+ atmel_uart_writel(port, ATMEL_US_IER, atmel_port->cache.imr);
+ atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->cache.brgr);
+ atmel_uart_writel(port, atmel_port->rtor,
+ atmel_port->cache.rtor);
+ atmel_uart_writel(port, ATMEL_US_TTGR, atmel_port->cache.ttgr);
+
+ if (atmel_port->fifo_size) {
+ atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_FIFOEN |
+ ATMEL_US_RXFCLR | ATMEL_US_TXFLCLR);
+ atmel_uart_writel(port, ATMEL_US_FMR,
+ atmel_port->cache.fmr);
+ atmel_uart_writel(port, ATMEL_US_FIER,
+ atmel_port->cache.fimr);
+ }
+ atmel_start_rx(port);
+ }
+
spin_lock_irqsave(&atmel_port->lock_suspended, flags);
if (atmel_port->pending) {
atmel_handle_receive(port, atmel_port->pending);
--
2.11.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] tty/serial: atmel: ensure state is restored after suspending
2017-02-03 22:53 [PATCH] tty/serial: atmel: ensure state is restored after suspending Alexandre Belloni
@ 2017-02-06 9:31 ` Nicolas Ferre
2017-02-06 11:10 ` Richard Genoud
1 sibling, 0 replies; 3+ messages in thread
From: Nicolas Ferre @ 2017-02-06 9:31 UTC (permalink / raw)
To: Alexandre Belloni, Richard Genoud
Cc: Greg Kroah-Hartman, linux-arm-kernel, linux-serial, linux-kernel
Le 03/02/2017 à 23:53, Alexandre Belloni a écrit :
> When going to suspend, the UART registers may be lost because the power to
> VDDcore is cut. This is not an issue in the normal case but when
> no_console_suspend is used, we need to restore the registers in order to
> get a functional console.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Reviewed-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Thanks,
> ---
> drivers/tty/serial/atmel_serial.c | 44 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index 168b10cad47b..22e0a73c0cb7 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -175,6 +175,17 @@ struct atmel_uart_port {
> unsigned int pending_status;
> spinlock_t lock_suspended;
>
> + struct {
> + u32 cr;
> + u32 mr;
> + u32 imr;
> + u32 brgr;
> + u32 rtor;
> + u32 ttgr;
> + u32 fmr;
> + u32 fimr;
> + } cache;
> +
> int (*prepare_rx)(struct uart_port *port);
> int (*prepare_tx)(struct uart_port *port);
> void (*schedule_rx)(struct uart_port *port);
> @@ -2649,6 +2660,20 @@ static int atmel_serial_suspend(struct platform_device *pdev,
> cpu_relax();
> }
>
> + if (atmel_is_console_port(port) && !console_suspend_enabled) {
> + /* Cache register values as we won't get a full shutdown/startup
> + * cycle
> + */
> + atmel_port->cache.mr = atmel_uart_readl(port, ATMEL_US_MR);
> + atmel_port->cache.imr = atmel_uart_readl(port, ATMEL_US_IMR);
> + atmel_port->cache.brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
> + atmel_port->cache.rtor = atmel_uart_readl(port,
> + atmel_port->rtor);
> + atmel_port->cache.ttgr = atmel_uart_readl(port, ATMEL_US_TTGR);
> + atmel_port->cache.fmr = atmel_uart_readl(port, ATMEL_US_FMR);
> + atmel_port->cache.fimr = atmel_uart_readl(port, ATMEL_US_FIMR);
> + }
> +
> /* we can not wake up if we're running on slow clock */
> atmel_port->may_wakeup = device_may_wakeup(&pdev->dev);
> if (atmel_serial_clk_will_stop()) {
> @@ -2671,6 +2696,25 @@ static int atmel_serial_resume(struct platform_device *pdev)
> struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> unsigned long flags;
>
> + if (atmel_is_console_port(port) && !console_suspend_enabled) {
> + atmel_uart_writel(port, ATMEL_US_MR, atmel_port->cache.mr);
> + atmel_uart_writel(port, ATMEL_US_IER, atmel_port->cache.imr);
> + atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->cache.brgr);
> + atmel_uart_writel(port, atmel_port->rtor,
> + atmel_port->cache.rtor);
> + atmel_uart_writel(port, ATMEL_US_TTGR, atmel_port->cache.ttgr);
> +
> + if (atmel_port->fifo_size) {
> + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_FIFOEN |
> + ATMEL_US_RXFCLR | ATMEL_US_TXFLCLR);
> + atmel_uart_writel(port, ATMEL_US_FMR,
> + atmel_port->cache.fmr);
> + atmel_uart_writel(port, ATMEL_US_FIER,
> + atmel_port->cache.fimr);
> + }
> + atmel_start_rx(port);
> + }
> +
> spin_lock_irqsave(&atmel_port->lock_suspended, flags);
> if (atmel_port->pending) {
> atmel_handle_receive(port, atmel_port->pending);
>
--
Nicolas Ferre
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tty/serial: atmel: ensure state is restored after suspending
2017-02-03 22:53 [PATCH] tty/serial: atmel: ensure state is restored after suspending Alexandre Belloni
2017-02-06 9:31 ` Nicolas Ferre
@ 2017-02-06 11:10 ` Richard Genoud
1 sibling, 0 replies; 3+ messages in thread
From: Richard Genoud @ 2017-02-06 11:10 UTC (permalink / raw)
To: Alexandre Belloni
Cc: Greg Kroah-Hartman, Nicolas Ferre, linux-arm-kernel, linux-serial,
linux-kernel
Hi Alexandre,
On 03/02/2017 23:53, Alexandre Belloni wrote:
> When going to suspend, the UART registers may be lost because the power to
> VDDcore is cut. This is not an issue in the normal case but when
> no_console_suspend is used, we need to restore the registers in order to
> get a functional console.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
> drivers/tty/serial/atmel_serial.c | 44 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index 168b10cad47b..22e0a73c0cb7 100644
> --- a/drivers/tty/serial/atmel_serial.c
> +++ b/drivers/tty/serial/atmel_serial.c
> @@ -175,6 +175,17 @@ struct atmel_uart_port {
> unsigned int pending_status;
> spinlock_t lock_suspended;
>
> + struct {
> + u32 cr;
> + u32 mr;
> + u32 imr;
> + u32 brgr;
> + u32 rtor;
> + u32 ttgr;
> + u32 fmr;
> + u32 fimr;
> + } cache;
> +
As struct cache is only used in suspend()/resume() we could add:
#ifdef CONFIG_PM / #endif
to remove it from atmel_uart_port when PM is not selected.
Even if I'm not a big fan of ifdefs, the suspend code is already
compiled out with #ifdef CONFIG_PM, so, at least, it would be consistent.
> int (*prepare_rx)(struct uart_port *port);
> int (*prepare_tx)(struct uart_port *port);
> void (*schedule_rx)(struct uart_port *port);
> @@ -2649,6 +2660,20 @@ static int atmel_serial_suspend(struct platform_device *pdev,
> cpu_relax();
> }
>
> + if (atmel_is_console_port(port) && !console_suspend_enabled) {
> + /* Cache register values as we won't get a full shutdown/startup
> + * cycle
> + */
> + atmel_port->cache.mr = atmel_uart_readl(port, ATMEL_US_MR);
> + atmel_port->cache.imr = atmel_uart_readl(port, ATMEL_US_IMR);
> + atmel_port->cache.brgr = atmel_uart_readl(port, ATMEL_US_BRGR);
> + atmel_port->cache.rtor = atmel_uart_readl(port,
> + atmel_port->rtor);
> + atmel_port->cache.ttgr = atmel_uart_readl(port, ATMEL_US_TTGR);
> + atmel_port->cache.fmr = atmel_uart_readl(port, ATMEL_US_FMR);
> + atmel_port->cache.fimr = atmel_uart_readl(port, ATMEL_US_FIMR);
> + }
> +
> /* we can not wake up if we're running on slow clock */
> atmel_port->may_wakeup = device_may_wakeup(&pdev->dev);
> if (atmel_serial_clk_will_stop()) {
> @@ -2671,6 +2696,25 @@ static int atmel_serial_resume(struct platform_device *pdev)
> struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
> unsigned long flags;
>
> + if (atmel_is_console_port(port) && !console_suspend_enabled) {
> + atmel_uart_writel(port, ATMEL_US_MR, atmel_port->cache.mr);
> + atmel_uart_writel(port, ATMEL_US_IER, atmel_port->cache.imr);
> + atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->cache.brgr);
> + atmel_uart_writel(port, atmel_port->rtor,
> + atmel_port->cache.rtor);
> + atmel_uart_writel(port, ATMEL_US_TTGR, atmel_port->cache.ttgr);
> +
> + if (atmel_port->fifo_size) {
> + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_FIFOEN |
> + ATMEL_US_RXFCLR | ATMEL_US_TXFLCLR);
> + atmel_uart_writel(port, ATMEL_US_FMR,
> + atmel_port->cache.fmr);
> + atmel_uart_writel(port, ATMEL_US_FIER,
> + atmel_port->cache.fimr);
> + }
> + atmel_start_rx(port);
> + }
> +
> spin_lock_irqsave(&atmel_port->lock_suspended, flags);
> if (atmel_port->pending) {
> atmel_handle_receive(port, atmel_port->pending);
>
Thanks !
Richard.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2017-02-03 22:53 [PATCH] tty/serial: atmel: ensure state is restored after suspending Alexandre Belloni
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2017-02-06 11:10 ` Richard Genoud
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