2014-10-13 10:01:19

by Jingchang Lu

Subject: [PATCHv3] serial: of-serial: fix up PM ops on no_console_suspend and port type

This patch fixes commit 2dea53bf57783f243c892e99c10c6921e956aa7e,
"serial: of-serial: add PM suspend/resume support", which disables
the uart clock on suspend, but also causes a hardware hang on register
access if no_console_suspend command line option is used.

Also, not every of_serial device is an 8250 port, so the serial8250
suspend/resume functions should only be applied to a real 8250 port.

Signed-off-by: Jingchang Lu <[email protected]>
---
changes in v3:
fix up point reference and deference.

changes in v2:
add switch selection on uart type.

drivers/tty/serial/of_serial.c | 42 ++++++++++++++++++++++++++++++++++++------
1 file changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index 8bc2563..9d747a7 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -245,9 +245,24 @@ static int of_serial_suspend(struct device *dev)
{
struct of_serial_info *info = dev_get_drvdata(dev);

- serial8250_suspend_port(info->line);
- if (info->clk)
- clk_disable_unprepare(info->clk);
+ switch(info->type) {
+#ifdef CONFIG_SERIAL_8250
+ case PORT_8250 ... PORT_MAX_8250:
+ {
+ struct uart_8250_port *port8250;
+ port8250 = serial8250_get_port(info->line);
+
+ serial8250_suspend_port(info->line);
+ if (info->clk &&
+ (!uart_console(&port8250->port) ||
+ (uart_console(&port8250->port) && console_suspend_enabled)))
+ clk_disable_unprepare(info->clk);
+ break;
+ }
+#endif
+ default:
+ break;
+ }

return 0;
}
@@ -256,10 +271,25 @@ static int of_serial_resume(struct device *dev)
{
struct of_serial_info *info = dev_get_drvdata(dev);

- if (info->clk)
- clk_prepare_enable(info->clk);
+ switch(info->type) {
+#ifdef CONFIG_SERIAL_8250
+ case PORT_8250 ... PORT_MAX_8250:
+ {
+ struct uart_8250_port *port8250;
+ port8250 = serial8250_get_port(info->line);
+
+ if (info->clk &&
+ (!uart_console(&port8250->port) ||
+ (uart_console(&port8250->port) && console_suspend_enabled)))
+ clk_prepare_enable(info->clk);

- serial8250_resume_port(info->line);
+ serial8250_resume_port(info->line);
+ break;
+ }
+#endif
+ default:
+ break;
+ }

return 0;
}
--
1.8.0

2014-10-13 12:01:16

by Peter Hurley

Subject: Re: [PATCHv3] serial: of-serial: fix up PM ops on no_console_suspend and port type

On 10/13/2014 05:14 AM, Jingchang Lu wrote:
> This patch fixes commit 2dea53bf57783f243c892e99c10c6921e956aa7e,
> "serial: of-serial: add PM suspend/resume support", which disables
> the uart clock on suspend, but also causes a hardware hang on register
> access if no_console_suspend command line option is used.
>
> Also, not every of_serial device is an 8250 port, so the serial8250
> suspend/resume functions should only be applied to a real 8250 port.
>
> Signed-off-by: Jingchang Lu <[email protected]>
> ---
> changes in v3:
> fix up point reference and deference.
>
> changes in v2:
> add switch selection on uart type.
>
> drivers/tty/serial/of_serial.c | 42 ++++++++++++++++++++++++++++++++++++------
> 1 file changed, 36 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
> index 8bc2563..9d747a7 100644
> --- a/drivers/tty/serial/of_serial.c
> +++ b/drivers/tty/serial/of_serial.c
> @@ -245,9 +245,24 @@ static int of_serial_suspend(struct device *dev)
> {
> struct of_serial_info *info = dev_get_drvdata(dev);
>
> - serial8250_suspend_port(info->line);
> - if (info->clk)
> - clk_disable_unprepare(info->clk);
> + switch(info->type) {
> +#ifdef CONFIG_SERIAL_8250
> + case PORT_8250 ... PORT_MAX_8250:
> + {
> + struct uart_8250_port *port8250;
> + port8250 = serial8250_get_port(info->line);
> +
> + serial8250_suspend_port(info->line);
> + if (info->clk &&
> + (!uart_console(&port8250->port) ||
> + (uart_console(&port8250->port) && console_suspend_enabled)))

This conditional is the same as

if (info->clk && (!uart_console(&port8250->port) || console_suspend_enabled))

> + clk_disable_unprepare(info->clk);
> + break;
> + }
> +#endif
> + default:
> + break;
> + }

I suggest you separate this into a separate function like:

#ifdef CONFIG_SERIAL_8250
static void of_serial_suspend_8250(struct of_serial_info *info)
{
struct uart_8250_port *uart = serial_8250_get_port(info->line);
struct uart_port *port = &uart->port;

serial8250_suspend_port(info->line);
if (info->clk && (!uart_console(port) || console_suspend_enabled))
clk_disable_unprepare(info->clk);
}
#else
static inline void of_serial_suspend_8250(struct of_serial_info *info)
{ }
#endif

and call it like:

static int of_serial_suspend(struct device *dev)
{
struct of_serial_info *info = dev_get_drvdata(dev);

switch (info->type) {
case PORT_8250 ... PORT_MAX_8250:
of_serial_suspend_8250(info);
break;
}

return 0;
}

I did not build-test this, so you should.

Regards,
Peter Hurley

>
> return 0;
> }
> @@ -256,10 +271,25 @@ static int of_serial_resume(struct device *dev)
> {
> struct of_serial_info *info = dev_get_drvdata(dev);
>
> - if (info->clk)
> - clk_prepare_enable(info->clk);
> + switch(info->type) {
> +#ifdef CONFIG_SERIAL_8250
> + case PORT_8250 ... PORT_MAX_8250:
> + {
> + struct uart_8250_port *port8250;
> + port8250 = serial8250_get_port(info->line);
> +
> + if (info->clk &&
> + (!uart_console(&port8250->port) ||
> + (uart_console(&port8250->port) && console_suspend_enabled)))
> + clk_prepare_enable(info->clk);
>
> - serial8250_resume_port(info->line);
> + serial8250_resume_port(info->line);
> + break;
> + }
> +#endif
> + default:
> + break;
> + }
>
> return 0;
> }
>