Mandatorily disabling the uart clock will cause register access
hung on "no_console_suspend". This patch add condition check on
it and only disable the clock with console_suspend_enabled true.
Signed-off-by: Joseph Lo <[email protected]>
Signed-off-by: Jingchang Lu <[email protected]>
---
drivers/tty/serial/of_serial.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index 8bc2563..a765399 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -246,7 +246,7 @@ 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)
+ if (info->clk && console_suspend_enabled)
clk_disable_unprepare(info->clk);
return 0;
@@ -256,7 +256,7 @@ static int of_serial_resume(struct device *dev)
{
struct of_serial_info *info = dev_get_drvdata(dev);
- if (info->clk)
+ if (info->clk && console_suspend_enabled)
clk_prepare_enable(info->clk);
serial8250_resume_port(info->line);
--
1.8.0
On 10/09/2014 02:10 AM, Jingchang Lu wrote:
> Mandatorily disabling the uart clock will cause register access
> hung on "no_console_suspend". This patch add condition check on
> it and only disable the clock with console_suspend_enabled true.
It would be useful if the email/patch subject line said "V2", and there
was a changelog below.
> Signed-off-by: Joseph Lo <[email protected]>
I don't think he did; he just suggested a small fix.
> Signed-off-by: Jingchang Lu <[email protected]>
> ---
> drivers/tty/serial/of_serial.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
...
>-----Original Message-----
>From: Stephen Warren [mailto:[email protected]]
>Sent: Friday, October 10, 2014 1:05 PM
>To: Lu Jingchang-B35083; [email protected]
>Cc: [email protected]; Joseph Lo; [email protected]; linux-
>[email protected]; [email protected]
>Subject: Re: [PATCH] serial: of-serial: fix up PM ops on
>no_console_suspend
>
>On 10/09/2014 02:10 AM, Jingchang Lu wrote:
>> Mandatorily disabling the uart clock will cause register access hung
>> on "no_console_suspend". This patch add condition check on it and only
>> disable the clock with console_suspend_enabled true.
>
>It would be useful if the email/patch subject line said "V2", and there
>was a changelog below.
This is not a v2, patch "serial: of-serial: add PM suspend/resume support
(commit 2dea53bf57783f243c892e99c10c6921e956aa7e)" has been merged into
linux-next tree, this is a fixup on that PM ops.
Thanks.
Best Regards,
Jingchang
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On 10/10/2014 02:16 AM, Jingchang Lu wrote:
>> From: Stephen Warren [mailto:[email protected]]
>> On 10/09/2014 02:10 AM, Jingchang Lu wrote:
>>> Mandatorily disabling the uart clock will cause register access hung
>>> on "no_console_suspend". This patch add condition check on it and only
>>> disable the clock with console_suspend_enabled true.
>>
>> It would be useful if the email/patch subject line said "V2", and there
>> was a changelog below.
> This is not a v2, patch "serial: of-serial: add PM suspend/resume support
> (commit 2dea53bf57783f243c892e99c10c6921e956aa7e)" has been merged into
> linux-next tree, this is a fixup on that PM ops.
Then please say so in the commit log. Something like,
Fix 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.
Regards,
Peter Hurley
Hi Jingchang,
On 10/09/2014 05:10 AM, Jingchang Lu wrote:
> Mandatorily disabling the uart clock will cause register access
> hung on "no_console_suspend". This patch add condition check on
> it and only disable the clock with console_suspend_enabled true.
>
> Signed-off-by: Joseph Lo <[email protected]>
> Signed-off-by: Jingchang Lu <[email protected]>
> ---
> drivers/tty/serial/of_serial.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
> index 8bc2563..a765399 100644
> --- a/drivers/tty/serial/of_serial.c
> +++ b/drivers/tty/serial/of_serial.c
> @@ -246,7 +246,7 @@ 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)
> + if (info->clk && console_suspend_enabled)
> clk_disable_unprepare(info->clk);
This needs to check that _this_ port is the console port, like:
if (info->clk && uart_console(port) && and console_suspend_enabled)
clk_disable_unprepare(info->clk);
which means you need something like:
struct uart_8250_port *uart = serial8250_get_port(info->line);
struct uart_port *port = &uart->port;
Also, there's another problem with your original patch:
not every of_serial device is an 8250, right?
serial8250_suspend_port() on a port that's not registered with 8250 core
is probably going to blow up.
Which means the body of of_platform_suspend() and of_platform_resume()
should probably look like
switch (info->type) {
#ifdef CONFIG_SERIAL_8250
case PORT_8250 ... PORT_MAX_8250:
{
/* current body of function */
}
#endif
default:
}
Regards,
Peter Hurley
>
> return 0;
> @@ -256,7 +256,7 @@ static int of_serial_resume(struct device *dev)
> {
> struct of_serial_info *info = dev_get_drvdata(dev);
>
> - if (info->clk)
> + if (info->clk && console_suspend_enabled)
> clk_prepare_enable(info->clk);
>
> serial8250_resume_port(info->line);
>
>-----Original Message-----
>From: Peter Hurley [mailto:[email protected]]
>Sent: Friday, October 10, 2014 7:39 PM
>To: Lu Jingchang-B35083; [email protected]
>Cc: [email protected]; [email protected]; linux-arm-
>[email protected]; [email protected]; Joseph Lo
>Subject: Re: [PATCH] serial: of-serial: fix up PM ops on
>no_console_suspend
>
>Hi Jingchang,
>
>On 10/09/2014 05:10 AM, Jingchang Lu wrote:
>> Mandatorily disabling the uart clock will cause register access hung
>> on "no_console_suspend". This patch add condition check on it and only
>> disable the clock with console_suspend_enabled true.
>>
>> Signed-off-by: Joseph Lo <[email protected]>
>> Signed-off-by: Jingchang Lu <[email protected]>
>> ---
>> drivers/tty/serial/of_serial.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/tty/serial/of_serial.c
>> b/drivers/tty/serial/of_serial.c index 8bc2563..a765399 100644
>> --- a/drivers/tty/serial/of_serial.c
>> +++ b/drivers/tty/serial/of_serial.c
>> @@ -246,7 +246,7 @@ 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)
>> + if (info->clk && console_suspend_enabled)
>> clk_disable_unprepare(info->clk);
>
>This needs to check that _this_ port is the console port, like:
>
> if (info->clk && uart_console(port) && and console_suspend_enabled)
> clk_disable_unprepare(info->clk);
>
>which means you need something like:
>
> struct uart_8250_port *uart = serial8250_get_port(info->line);
> struct uart_port *port = &uart->port;
>
>Also, there's another problem with your original patch:
>not every of_serial device is an 8250, right?
>serial8250_suspend_port() on a port that's not registered with 8250 core
>is probably going to blow up.
>
>Which means the body of of_platform_suspend() and of_platform_resume()
>should probably look like
>
> switch (info->type) {
>#ifdef CONFIG_SERIAL_8250
> case PORT_8250 ... PORT_MAX_8250:
> {
> /* current body of function */
> }
>#endif
> default:
> }
>
Yes, this should be considered, then serial8250_get_port(info->line) for uart_console() also
should be put in this type switch, Thanks.
Best Regards,
Jingchang
>Regards,
>Peter Hurley
>
>
>>
>> return 0;
>> @@ -256,7 +256,7 @@ static int of_serial_resume(struct device *dev) {
>> struct of_serial_info *info = dev_get_drvdata(dev);
>>
>> - if (info->clk)
>> + if (info->clk && console_suspend_enabled)
>> clk_prepare_enable(info->clk);
>>
>> serial8250_resume_port(info->line);
>>
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