[V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Vijaya Krishna Nivarthi]

For the case of console_suspend disabled, if back to back suspend/resume
test is executed, at the end of test, sometimes console would appear to
be frozen not responding to input. This would happen because, during
resume, rx transactions can come in before system is ready, malfunction
of rx happens in turn resulting in console appearing to be stuck.

Do a stop_rx in suspend sequence to prevent this.

Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
---
v4: moved the change to serial core to apply for all drivers
v3: swapped the order of conditions to be more human readable
v2: restricted patch to contain only stop_rx in suspend sequence
v1: intial patch contained 2 additional unrelated changes in vicinity
---
 drivers/tty/serial/serial_core.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 82a1770..9a85b41 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2211,9 +2211,16 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
 	}
 	put_device(tty_dev);
 
-	/* Nothing to do if the console is not suspending */
-	if (!console_suspend_enabled && uart_console(uport))
+	/*
+	 * Nothing to do if the console is not suspending
+	 * except stop_rx to prevent any asynchronous data
+	 * over RX line. Re-start_rx, when required, is
+	 * done by set_termios in resume sequence
+	 */
+	if (!console_suspend_enabled && uart_console(uport)) {
+		uport->ops->stop_rx(uport);
 		goto unlock;
+	}
 
 	uport->suspended = 1;
 
-- 
Qualcomm INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by the Linux Foundation.

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Marek Szyprowski]

Hi,

On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
> For the case of console_suspend disabled, if back to back suspend/resume
> test is executed, at the end of test, sometimes console would appear to
> be frozen not responding to input. This would happen because, during
> resume, rx transactions can come in before system is ready, malfunction
> of rx happens in turn resulting in console appearing to be stuck.
>
> Do a stop_rx in suspend sequence to prevent this.
>
> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
> ---
> v4: moved the change to serial core to apply for all drivers
> v3: swapped the order of conditions to be more human readable
> v2: restricted patch to contain only stop_rx in suspend sequence
> v1: intial patch contained 2 additional unrelated changes in vicinity
> ---

This patch landed recently in linux-next as commit c9d2325cdb92 
("serial: core: Do stop_rx in suspend path for console if 
console_suspend is disabled").

Unfortunately it breaks console operation on my test systems after 
system suspend/resume cycle if 'no_console_suspend' kernel parameter is 
present. System properly resumes from suspend, the console displays all 
the messages and even command line prompt, but then doesn't react on any 
input. If I remove the 'no_console_suspend' parameter, the console is 
again operational after system suspend/resume cycle. Before this patch 
it worked fine regardless the 'no_console_suspend' parameter.

If this matters, the test system is ARM 32bit Samsung Exynos5422-based 
Odroid XU3lite board.

>   drivers/tty/serial/serial_core.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 82a1770..9a85b41 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -2211,9 +2211,16 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
>   	}
>   	put_device(tty_dev);
>   
> -	/* Nothing to do if the console is not suspending */
> -	if (!console_suspend_enabled && uart_console(uport))
> +	/*
> +	 * Nothing to do if the console is not suspending
> +	 * except stop_rx to prevent any asynchronous data
> +	 * over RX line. Re-start_rx, when required, is
> +	 * done by set_termios in resume sequence
> +	 */
> +	if (!console_suspend_enabled && uart_console(uport)) {
> +		uport->ops->stop_rx(uport);
>   		goto unlock;
> +	}
>   
>   	uport->suspended = 1;
>   

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Marek Szyprowski]

On 23.05.2022 23:32, Marek Szyprowski wrote:
> Hi,
>
> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
>> For the case of console_suspend disabled, if back to back suspend/resume
>> test is executed, at the end of test, sometimes console would appear to
>> be frozen not responding to input. This would happen because, during
>> resume, rx transactions can come in before system is ready, malfunction
>> of rx happens in turn resulting in console appearing to be stuck.
>>
>> Do a stop_rx in suspend sequence to prevent this.
>>
>> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
>> ---
>> v4: moved the change to serial core to apply for all drivers
>> v3: swapped the order of conditions to be more human readable
>> v2: restricted patch to contain only stop_rx in suspend sequence
>> v1: intial patch contained 2 additional unrelated changes in vicinity
>> ---
>
> This patch landed recently in linux-next as commit c9d2325cdb92 
> ("serial: core: Do stop_rx in suspend path for console if 
> console_suspend is disabled").
>
> Unfortunately it breaks console operation on my test systems after 
> system suspend/resume cycle if 'no_console_suspend' kernel parameter 
> is present. System properly resumes from suspend, the console displays 
> all the messages and even command line prompt, but then doesn't react 
> on any input. If I remove the 'no_console_suspend' parameter, the 
> console is again operational after system suspend/resume cycle. Before 
> this patch it worked fine regardless the 'no_console_suspend' parameter.
>
> If this matters, the test system is ARM 32bit Samsung Exynos5422-based 
> Odroid XU3lite board.


One more information. This issue can be easily reproduced with QEMU. It 
happens both on ARM 32bit and ARM 64bit QEMU's 'virt' machines when 
'no_console_suspend' is added to kernel's cmdline.


>
>>   drivers/tty/serial/serial_core.c | 11 +++++++++--
>>   1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/tty/serial/serial_core.c 
>> b/drivers/tty/serial/serial_core.c
>> index 82a1770..9a85b41 100644
>> --- a/drivers/tty/serial/serial_core.c
>> +++ b/drivers/tty/serial/serial_core.c
>> @@ -2211,9 +2211,16 @@ int uart_suspend_port(struct uart_driver *drv, 
>> struct uart_port *uport)
>>       }
>>       put_device(tty_dev);
>>   -    /* Nothing to do if the console is not suspending */
>> -    if (!console_suspend_enabled && uart_console(uport))
>> +    /*
>> +     * Nothing to do if the console is not suspending
>> +     * except stop_rx to prevent any asynchronous data
>> +     * over RX line. Re-start_rx, when required, is
>> +     * done by set_termios in resume sequence
>> +     */
>> +    if (!console_suspend_enabled && uart_console(uport)) {
>> +        uport->ops->stop_rx(uport);
>>           goto unlock;
>> +    }
>>         uport->suspended = 1;
>
> Best regards

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Vijaya Krishna Nivarthi]

Hi,

On 5/24/2022 5:24 PM, Marek Szyprowski wrote:
> On 23.05.2022 23:32, Marek Szyprowski wrote:
>> Hi,
>>
>> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
>>> For the case of console_suspend disabled, if back to back suspend/resume
>>> test is executed, at the end of test, sometimes console would appear to
>>> be frozen not responding to input. This would happen because, during
>>> resume, rx transactions can come in before system is ready, malfunction
>>> of rx happens in turn resulting in console appearing to be stuck.
>>>
>>> Do a stop_rx in suspend sequence to prevent this.
>>>
>>> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
>>> ---
>>> v4: moved the change to serial core to apply for all drivers
>>> v3: swapped the order of conditions to be more human readable
>>> v2: restricted patch to contain only stop_rx in suspend sequence
>>> v1: intial patch contained 2 additional unrelated changes in vicinity
>>> ---
>> This patch landed recently in linux-next as commit c9d2325cdb92
>> ("serial: core: Do stop_rx in suspend path for console if
>> console_suspend is disabled").
>>
>> Unfortunately it breaks console operation on my test systems after
>> system suspend/resume cycle if 'no_console_suspend' kernel parameter
>> is present. System properly resumes from suspend, the console displays
>> all the messages and even command line prompt, but then doesn't react
>> on any input. If I remove the 'no_console_suspend' parameter, the
>> console is again operational after system suspend/resume cycle. Before
>> this patch it worked fine regardless the 'no_console_suspend' parameter.
>>
>> If this matters, the test system is ARM 32bit Samsung Exynos5422-based
>> Odroid XU3lite board.
>
> One more information. This issue can be easily reproduced with QEMU. It
> happens both on ARM 32bit and ARM 64bit QEMU's 'virt' machines when
> 'no_console_suspend' is added to kernel's cmdline.
>
Ideally, as comments indicate, the set_termios should have done stop_rx 
at begin and start_rx at end to take care of this issue.

This is probably missing in your driver. Can we check if this can be 
fixed? OR other option is

Add a start_rx in uart_resume_port after call to set_termios to handle 
this scenario for other drivers.

Please let me know if there are any concerns for this options.

>>>    drivers/tty/serial/serial_core.c | 11 +++++++++--
>>>    1 file changed, 9 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/serial_core.c
>>> b/drivers/tty/serial/serial_core.c
>>> index 82a1770..9a85b41 100644
>>> --- a/drivers/tty/serial/serial_core.c
>>> +++ b/drivers/tty/serial/serial_core.c
>>> @@ -2211,9 +2211,16 @@ int uart_suspend_port(struct uart_driver *drv,
>>> struct uart_port *uport)
>>>        }
>>>        put_device(tty_dev);
>>>    -    /* Nothing to do if the console is not suspending */
>>> -    if (!console_suspend_enabled && uart_console(uport))
>>> +    /*
>>> +     * Nothing to do if the console is not suspending
>>> +     * except stop_rx to prevent any asynchronous data
>>> +     * over RX line. Re-start_rx, when required, is
>>> +     * done by set_termios in resume sequence
>>> +     */
>>> +    if (!console_suspend_enabled && uart_console(uport)) {
>>> +        uport->ops->stop_rx(uport);
>>>            goto unlock;
>>> +    }
>>>          uport->suspended = 1;
>> Best regards
> Best regards
Thank you.

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Marek Szyprowski]

Hi,

On 01.06.2022 13:24, Vijaya Krishna Nivarthi wrote:
> On 5/24/2022 5:24 PM, Marek Szyprowski wrote:
>> On 23.05.2022 23:32, Marek Szyprowski wrote:
>>> Hi,
>>>
>>> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
>>>> For the case of console_suspend disabled, if back to back 
>>>> suspend/resume
>>>> test is executed, at the end of test, sometimes console would 
>>>> appear to
>>>> be frozen not responding to input. This would happen because, during
>>>> resume, rx transactions can come in before system is ready, 
>>>> malfunction
>>>> of rx happens in turn resulting in console appearing to be stuck.
>>>>
>>>> Do a stop_rx in suspend sequence to prevent this.
>>>>
>>>> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
>>>> ---
>>>> v4: moved the change to serial core to apply for all drivers
>>>> v3: swapped the order of conditions to be more human readable
>>>> v2: restricted patch to contain only stop_rx in suspend sequence
>>>> v1: intial patch contained 2 additional unrelated changes in vicinity
>>>> ---
>>> This patch landed recently in linux-next as commit c9d2325cdb92
>>> ("serial: core: Do stop_rx in suspend path for console if
>>> console_suspend is disabled").
>>>
>>> Unfortunately it breaks console operation on my test systems after
>>> system suspend/resume cycle if 'no_console_suspend' kernel parameter
>>> is present. System properly resumes from suspend, the console displays
>>> all the messages and even command line prompt, but then doesn't react
>>> on any input. If I remove the 'no_console_suspend' parameter, the
>>> console is again operational after system suspend/resume cycle. Before
>>> this patch it worked fine regardless the 'no_console_suspend' 
>>> parameter.
>>>
>>> If this matters, the test system is ARM 32bit Samsung Exynos5422-based
>>> Odroid XU3lite board.
>>
>> One more information. This issue can be easily reproduced with QEMU. It
>> happens both on ARM 32bit and ARM 64bit QEMU's 'virt' machines when
>> 'no_console_suspend' is added to kernel's cmdline.
>>
> Ideally, as comments indicate, the set_termios should have done 
> stop_rx at begin and start_rx at end to take care of this issue.
>
> This is probably missing in your driver. Can we check if this can be 
> fixed? 

Sure, just point me what need to be added in amba-pl011.c and 
samsung_tty.c. I've briefly compared the suspend/resume paths of those 
drivers with other drivers and I don't see anything missing there.

> OR other option is
>
> Add a start_rx in uart_resume_port after call to set_termios to handle 
> this scenario for other drivers.
>
> Please let me know if there are any concerns for this options.

IMHO this looks like an issue that affects lots of drivers and it should 
be handled in the core.

 > ...

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Vijaya Krishna Nivarthi]

Hi,


On 6/2/2022 3:55 AM, Marek Szyprowski wrote:
> Hi,
>
> On 01.06.2022 13:24, Vijaya Krishna Nivarthi wrote:
>> On 5/24/2022 5:24 PM, Marek Szyprowski wrote:
>>> On 23.05.2022 23:32, Marek Szyprowski wrote:
>>>> Hi,
>>>>
>>>> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
>>>>> For the case of console_suspend disabled, if back to back
>>>>> suspend/resume
>>>>> test is executed, at the end of test, sometimes console would
>>>>> appear to
>>>>> be frozen not responding to input. This would happen because, during
>>>>> resume, rx transactions can come in before system is ready,
>>>>> malfunction
>>>>> of rx happens in turn resulting in console appearing to be stuck.
>>>>>
>>>>> Do a stop_rx in suspend sequence to prevent this.
>>>>>
>>>>> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
>>>>> ---
>>>>> v4: moved the change to serial core to apply for all drivers
>>>>> v3: swapped the order of conditions to be more human readable
>>>>> v2: restricted patch to contain only stop_rx in suspend sequence
>>>>> v1: intial patch contained 2 additional unrelated changes in vicinity
>>>>> ---
>>>> This patch landed recently in linux-next as commit c9d2325cdb92
>>>> ("serial: core: Do stop_rx in suspend path for console if
>>>> console_suspend is disabled").
>>>>
>>>> Unfortunately it breaks console operation on my test systems after
>>>> system suspend/resume cycle if 'no_console_suspend' kernel parameter
>>>> is present. System properly resumes from suspend, the console displays
>>>> all the messages and even command line prompt, but then doesn't react
>>>> on any input. If I remove the 'no_console_suspend' parameter, the
>>>> console is again operational after system suspend/resume cycle. Before
>>>> this patch it worked fine regardless the 'no_console_suspend'
>>>> parameter.
>>>>
>>>> If this matters, the test system is ARM 32bit Samsung Exynos5422-based
>>>> Odroid XU3lite board.
>>> One more information. This issue can be easily reproduced with QEMU. It
>>> happens both on ARM 32bit and ARM 64bit QEMU's 'virt' machines when
>>> 'no_console_suspend' is added to kernel's cmdline.
>>>
>> Ideally, as comments indicate, the set_termios should have done
>> stop_rx at begin and start_rx at end to take care of this issue.
>>
>> This is probably missing in your driver. Can we check if this can be
>> fixed?
> Sure, just point me what need to be added in amba-pl011.c and
> samsung_tty.c. I've briefly compared the suspend/resume paths of those
> drivers with other drivers and I don't see anything missing there.
>
>> OR other option is
>>
>> Add a start_rx in uart_resume_port after call to set_termios to handle
>> this scenario for other drivers.
>>
>> Please let me know if there are any concerns for this options.
> IMHO this looks like an issue that affects lots of drivers and it should
> be handled in the core.

Sure, we will look into both aspects and get back as soon as possible.

Thank you.

>
>   > ...
>
> Best regards

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Vijaya Krishna Nivarthi]

Hi,


On 6/2/2022 9:12 PM, Vijaya Krishna Nivarthi wrote:
> Hi,
>
>
> On 6/2/2022 3:55 AM, Marek Szyprowski wrote:
>> Hi,
>>
>> On 01.06.2022 13:24, Vijaya Krishna Nivarthi wrote:
>>> On 5/24/2022 5:24 PM, Marek Szyprowski wrote:
>>>> On 23.05.2022 23:32, Marek Szyprowski wrote:
>>>>> Hi,
>>>>>
>>>>> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
>>>>>> For the case of console_suspend disabled, if back to back
>>>>>> suspend/resume
>>>>>> test is executed, at the end of test, sometimes console would
>>>>>> appear to
>>>>>> be frozen not responding to input. This would happen because, during
>>>>>> resume, rx transactions can come in before system is ready,
>>>>>> malfunction
>>>>>> of rx happens in turn resulting in console appearing to be stuck.
>>>>>>
>>>>>> Do a stop_rx in suspend sequence to prevent this.
>>>>>>
>>>>>> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
>>>>>> ---
>>>>>> v4: moved the change to serial core to apply for all drivers
>>>>>> v3: swapped the order of conditions to be more human readable
>>>>>> v2: restricted patch to contain only stop_rx in suspend sequence
>>>>>> v1: intial patch contained 2 additional unrelated changes in 
>>>>>> vicinity
>>>>>> ---
>>>>> This patch landed recently in linux-next as commit c9d2325cdb92
>>>>> ("serial: core: Do stop_rx in suspend path for console if
>>>>> console_suspend is disabled").
>>>>>
>>>>> Unfortunately it breaks console operation on my test systems after
>>>>> system suspend/resume cycle if 'no_console_suspend' kernel parameter
>>>>> is present. System properly resumes from suspend, the console 
>>>>> displays
>>>>> all the messages and even command line prompt, but then doesn't react
>>>>> on any input. If I remove the 'no_console_suspend' parameter, the
>>>>> console is again operational after system suspend/resume cycle. 
>>>>> Before
>>>>> this patch it worked fine regardless the 'no_console_suspend'
>>>>> parameter.
>>>>>
>>>>> If this matters, the test system is ARM 32bit Samsung 
>>>>> Exynos5422-based
>>>>> Odroid XU3lite board.
>>>> One more information. This issue can be easily reproduced with 
>>>> QEMU. It
>>>> happens both on ARM 32bit and ARM 64bit QEMU's 'virt' machines when
>>>> 'no_console_suspend' is added to kernel's cmdline.
>>>>
>>> Ideally, as comments indicate, the set_termios should have done
>>> stop_rx at begin and start_rx at end to take care of this issue.
>>>
>>> This is probably missing in your driver. Can we check if this can be
>>> fixed?
>> Sure, just point me what need to be added in amba-pl011.c and
>> samsung_tty.c. I've briefly compared the suspend/resume paths of those
>> drivers with other drivers and I don't see anything missing there.
>>
>>> OR other option is
>>>
>>> Add a start_rx in uart_resume_port after call to set_termios to handle
>>> this scenario for other drivers.

Since start_rx is not exposed it doesn't seem like we will be able to 
handle it in core.

In your drivers, Can we add a call to stop_rx at begin of set_termios 
and then undo it at end?

That would ensure that set_termios functionality is unaffected while 
fixing the broken cases?

If that's not an option we will have to go back to a previous version of 
limiting the change to qcom driver.

Thank you.

>>>
>>> Please let me know if there are any concerns for this options.
>> IMHO this looks like an issue that affects lots of drivers and it should
>> be handled in the core.
>
> Sure, we will look into both aspects and get back as soon as possible.
>
> Thank you.
>
>>
>>   > ...
>>
>> Best regards

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Doug Anderson]

Hi,

On Fri, Jun 3, 2022 at 11:54 AM Vijaya Krishna Nivarthi
<quic_vnivarth@quicinc.com> wrote:
>
> >>> Add a start_rx in uart_resume_port after call to set_termios to handle
> >>> this scenario for other drivers.
>
> Since start_rx is not exposed it doesn't seem like we will be able to
> handle it in core.
>
> In your drivers, Can we add a call to stop_rx at begin of set_termios
> and then undo it at end?
>
> That would ensure that set_termios functionality is unaffected while
> fixing the broken cases?
>
> If that's not an option we will have to go back to a previous version of
> limiting the change to qcom driver.

How about this: add an optional start_rx() callback to "struct
uart_ops" and then only do your stop_rx() logic in uart_suspend_port()
if you'll be able to start it again (AKA if the start_rx() callback is
not NULL). That keeps the logic in the core.

-Doug

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Vijaya Krishna Nivarthi]

Hi,


On 6/4/2022 12:58 AM, Doug Anderson wrote:
> Hi,
>
> On Fri, Jun 3, 2022 at 11:54 AM Vijaya Krishna Nivarthi
> <quic_vnivarth@quicinc.com> wrote:
>>>>> Add a start_rx in uart_resume_port after call to set_termios to handle
>>>>> this scenario for other drivers.
>> Since start_rx is not exposed it doesn't seem like we will be able to
>> handle it in core.
>>
>> In your drivers, Can we add a call to stop_rx at begin of set_termios
>> and then undo it at end?
>>
>> That would ensure that set_termios functionality is unaffected while
>> fixing the broken cases?
>>
>> If that's not an option we will have to go back to a previous version of
>> limiting the change to qcom driver.
> How about this: add an optional start_rx() callback to "struct
> uart_ops" and then only do your stop_rx() logic in uart_suspend_port()
> if you'll be able to start it again (AKA if the start_rx() callback is
> not NULL). That keeps the logic in the core.

This seems good. Thank you.

And also conditionally call start_rx in uart_resume_port after call to 
set_termios?
I have tested such patch and it is working fine, will upload it.

-Vijay/

> -Doug

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Greg KH]

On Mon, May 23, 2022 at 11:32:46PM +0200, Marek Szyprowski wrote:
> Hi,
> 
> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
> > For the case of console_suspend disabled, if back to back suspend/resume
> > test is executed, at the end of test, sometimes console would appear to
> > be frozen not responding to input. This would happen because, during
> > resume, rx transactions can come in before system is ready, malfunction
> > of rx happens in turn resulting in console appearing to be stuck.
> >
> > Do a stop_rx in suspend sequence to prevent this.
> >
> > Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
> > ---
> > v4: moved the change to serial core to apply for all drivers
> > v3: swapped the order of conditions to be more human readable
> > v2: restricted patch to contain only stop_rx in suspend sequence
> > v1: intial patch contained 2 additional unrelated changes in vicinity
> > ---
> 
> This patch landed recently in linux-next as commit c9d2325cdb92 
> ("serial: core: Do stop_rx in suspend path for console if 
> console_suspend is disabled").
> 
> Unfortunately it breaks console operation on my test systems after 
> system suspend/resume cycle if 'no_console_suspend' kernel parameter is 
> present. System properly resumes from suspend, the console displays all 
> the messages and even command line prompt, but then doesn't react on any 
> input. If I remove the 'no_console_suspend' parameter, the console is 
> again operational after system suspend/resume cycle. Before this patch 
> it worked fine regardless the 'no_console_suspend' parameter.

Did this ever get resolved or do I need to revert this?

thanks,

greg k-h

Re: [V4] serial: core: Do stop_rx in suspend path for console if console_suspend is disabled

[Vijaya Krishna Nivarthi]

On 6/7/2022 6:52 PM, Greg KH wrote:
> On Mon, May 23, 2022 at 11:32:46PM +0200, Marek Szyprowski wrote:
>> Hi,
>>
>> On 16.05.2022 11:20, Vijaya Krishna Nivarthi wrote:
>>> For the case of console_suspend disabled, if back to back suspend/resume
>>> test is executed, at the end of test, sometimes console would appear to
>>> be frozen not responding to input. This would happen because, during
>>> resume, rx transactions can come in before system is ready, malfunction
>>> of rx happens in turn resulting in console appearing to be stuck.
>>>
>>> Do a stop_rx in suspend sequence to prevent this.
>>>
>>> Signed-off-by: Vijaya Krishna Nivarthi <quic_vnivarth@quicinc.com>
>>> ---
>>> v4: moved the change to serial core to apply for all drivers
>>> v3: swapped the order of conditions to be more human readable
>>> v2: restricted patch to contain only stop_rx in suspend sequence
>>> v1: intial patch contained 2 additional unrelated changes in vicinity
>>> ---
>> This patch landed recently in linux-next as commit c9d2325cdb92
>> ("serial: core: Do stop_rx in suspend path for console if
>> console_suspend is disabled").
>>
>> Unfortunately it breaks console operation on my test systems after
>> system suspend/resume cycle if 'no_console_suspend' kernel parameter is
>> present. System properly resumes from suspend, the console displays all
>> the messages and even command line prompt, but then doesn't react on any
>> input. If I remove the 'no_console_suspend' parameter, the console is
>> again operational after system suspend/resume cycle. Before this patch
>> it worked fine regardless the 'no_console_suspend' parameter.
> Did this ever get resolved or do I need to revert this?

We have a resolution and I will be uploading a Fixes: patch today.

Thank you.

-Vijay/


>
> thanks,
>
> greg k-h