* [PATCH] serial: core: stop passing NULL in uart_resume_port
@ 2018-07-25 10:04 Chen Hu
2018-07-25 22:01 ` Andy Shevchenko
0 siblings, 1 reply; 4+ messages in thread
From: Chen Hu @ 2018-07-25 10:04 UTC (permalink / raw)
Cc: Chen Hu, Greg Kroah-Hartman, Jiri Slaby, linux-serial, linux-kernel
We found the baud rate is changed after S3 on some Intel Broxton
platforms. The baud rate should be restored during resume. However, some
set_termios() callback such as dw8250_set_termios() for DesignWare 8250
will skip setting if old termios is NULL. We address this issue via
passing a dummy.
Signed-off-by: Chen Hu <hu1.chen@intel.com>
---
drivers/tty/serial/serial_core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index f02965936f2e..8b815f1539e8 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2217,6 +2217,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
struct device *tty_dev;
struct uart_match match = {uport, drv};
struct ktermios termios;
+ static struct ktermios dummy;
mutex_lock(&port->mutex);
@@ -2277,7 +2278,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
pm_runtime_put_autosuspend(uport->dev);
if (ret == 0) {
if (tty)
- uart_change_speed(tty, state, NULL);
+ uart_change_speed(tty, state, &dummy);
pm_runtime_get_sync(uport->dev);
spin_lock_irq(&uport->lock);
ops->set_mctrl(uport, uport->mctrl);
--
2.13.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] serial: core: stop passing NULL in uart_resume_port
2018-07-25 10:04 [PATCH] serial: core: stop passing NULL in uart_resume_port Chen Hu
@ 2018-07-25 22:01 ` Andy Shevchenko
2018-07-26 9:36 ` Chen Hu
0 siblings, 1 reply; 4+ messages in thread
From: Andy Shevchenko @ 2018-07-25 22:01 UTC (permalink / raw)
To: Chen Hu
Cc: Greg Kroah-Hartman, Jiri Slaby, open list:SERIAL DRIVERS,
Linux Kernel Mailing List
On Wed, Jul 25, 2018 at 1:04 PM, Chen Hu <hu1.chen@intel.com> wrote:
> We found the baud rate is changed after S3 on some Intel Broxton
> platforms. The baud rate should be restored during resume. However, some
> set_termios() callback such as dw8250_set_termios() for DesignWare 8250
> will skip setting if old termios is NULL. We address this issue via
> passing a dummy.
Why does it need to be "fixed" here then?
>
> Signed-off-by: Chen Hu <hu1.chen@intel.com>
> ---
> drivers/tty/serial/serial_core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index f02965936f2e..8b815f1539e8 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -2217,6 +2217,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
> struct device *tty_dev;
> struct uart_match match = {uport, drv};
> struct ktermios termios;
> + static struct ktermios dummy;
>
> mutex_lock(&port->mutex);
>
> @@ -2277,7 +2278,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
> pm_runtime_put_autosuspend(uport->dev);
> if (ret == 0) {
> if (tty)
> - uart_change_speed(tty, state, NULL);
> + uart_change_speed(tty, state, &dummy);
> pm_runtime_get_sync(uport->dev);
> spin_lock_irq(&uport->lock);
> ops->set_mctrl(uport, uport->mctrl);
> --
> 2.13.0
>
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] serial: core: stop passing NULL in uart_resume_port
2018-07-25 22:01 ` Andy Shevchenko
@ 2018-07-26 9:36 ` Chen Hu
2018-07-26 14:04 ` Andy Shevchenko
0 siblings, 1 reply; 4+ messages in thread
From: Chen Hu @ 2018-07-26 9:36 UTC (permalink / raw)
To: andy.shevchenko
Cc: Chen Hu, Greg Kroah-Hartman, Jiri Slaby, linux-serial, linux-kernel
Hi Andy,
Thanks the feedback.
Is it better to modify the DesignWare 8250 driver directly? Or do you think is this really an issue?
Thanks
Chen Hu
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] serial: core: stop passing NULL in uart_resume_port
2018-07-26 9:36 ` Chen Hu
@ 2018-07-26 14:04 ` Andy Shevchenko
0 siblings, 0 replies; 4+ messages in thread
From: Andy Shevchenko @ 2018-07-26 14:04 UTC (permalink / raw)
To: Chen Hu
Cc: Greg Kroah-Hartman, Jiri Slaby, open list:SERIAL DRIVERS,
Linux Kernel Mailing List
On Thu, Jul 26, 2018 at 12:36 PM, Chen Hu <hu1.chen@intel.com> wrote:
> Is it better to modify the DesignWare 8250 driver directly? Or do you think is this really an issue?
I have checked all of the users of do_termios in 8250 and only DW
bails out on old == NULL.
So, send a patch against 8250_dw with detailed explanation why it's
wrong (use case, examples of wrong output, etc) and how you fix it.
Describe any potential side effects (b/c it's a new behaviour).
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-07-26 14:04 UTC | newest]
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2018-07-25 10:04 [PATCH] serial: core: stop passing NULL in uart_resume_port Chen Hu
2018-07-25 22:01 ` Andy Shevchenko
2018-07-26 9:36 ` Chen Hu
2018-07-26 14:04 ` Andy Shevchenko
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