[PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Andre Werner]

Fix the IRQ check to treat the negative values as No IRQ.

Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
---
V2:
There are no changes to the patch itself. The previous patch submission
had a very weird structure within the discussion thread:
https://lkml.org/lkml/2025/1/16/398
This is simply a new thread opened for better handling.
---
 drivers/tty/serial/sc16is7xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 7b51cdc274fd..560f45ed19ae 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
 	/* Always ask for fixed clock rate from a property. */
 	device_property_read_u32(dev, "clock-frequency", &uartclk);
 
-	s->polling = !!irq;
+	s->polling = (irq <= 0);
 	if (s->polling)
 		dev_dbg(dev,
 			"No interrupt pin definition, falling back to polling mode\n");
-- 
2.48.0

Re: [PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Greg KH]

On Fri, Jan 17, 2025 at 06:18:22PM +0100, Andre Werner wrote:
> Fix the IRQ check to treat the negative values as No IRQ.
> 
> Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
> ---
> V2:
> There are no changes to the patch itself. The previous patch submission
> had a very weird structure within the discussion thread:
> https://lkml.org/lkml/2025/1/16/398
> This is simply a new thread opened for better handling.
> ---
>  drivers/tty/serial/sc16is7xx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> index 7b51cdc274fd..560f45ed19ae 100644
> --- a/drivers/tty/serial/sc16is7xx.c
> +++ b/drivers/tty/serial/sc16is7xx.c
> @@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
>  	/* Always ask for fixed clock rate from a property. */
>  	device_property_read_u32(dev, "clock-frequency", &uartclk);
>  
> -	s->polling = !!irq;
> +	s->polling = (irq <= 0);
>  	if (s->polling)
>  		dev_dbg(dev,
>  			"No interrupt pin definition, falling back to polling mode\n");
> -- 
> 2.48.0
> 
> 

What commit id does this "fix"?

thanks,

greg k-h

Re: [PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Jiri Slaby]

On 18. 01. 25, 8:34, Greg KH wrote:
> On Fri, Jan 17, 2025 at 06:18:22PM +0100, Andre Werner wrote:
>> Fix the IRQ check to treat the negative values as No IRQ.
>>
>> Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
>> ---
>> V2:
>> There are no changes to the patch itself. The previous patch submission
>> had a very weird structure within the discussion thread:
>> https://lkml.org/lkml/2025/1/16/398
>> This is simply a new thread opened for better handling.
>> ---
>>   drivers/tty/serial/sc16is7xx.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
>> index 7b51cdc274fd..560f45ed19ae 100644
>> --- a/drivers/tty/serial/sc16is7xx.c
>> +++ b/drivers/tty/serial/sc16is7xx.c
>> @@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
>>   	/* Always ask for fixed clock rate from a property. */
>>   	device_property_read_u32(dev, "clock-frequency", &uartclk);
>>   
>> -	s->polling = !!irq;
>> +	s->polling = (irq <= 0);
>>   	if (s->polling)
>>   		dev_dbg(dev,
>>   			"No interrupt pin definition, falling back to polling mode\n");
>> -- 
>> 2.48.0
>>
>>
> 
> What commit id does this "fix"?

And yet, it's worth noting (in the commit log) that it actually does not 
fix any real problem. It's only a sanity check, right?

-- 
js
suse labs

RE: [PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Maarten Brock]

> -----Original Message-----
> Fix the IRQ check to treat the negative values as No IRQ.

It seems to me that this is a real fix and needs a Fixes tag.
See below.

> Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
> ---
> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> index 7b51cdc274fd..560f45ed19ae 100644
> --- a/drivers/tty/serial/sc16is7xx.c
> +++ b/drivers/tty/serial/sc16is7xx.c
> @@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct
> sc16is7xx_devtype *devtype,
>  	/* Always ask for fixed clock rate from a property. */
>  	device_property_read_u32(dev, "clock-frequency", &uartclk);
> 
> -	s->polling = !!irq;
> +	s->polling = (irq <= 0);

When irq>=0 these two lines above have a different outcome!
irq==0   =>   !!irq==false   <=>   (irq<=0)==true
irq==1   =>   !!irq==true   <=>   (irq<=0)==false

>  	if (s->polling)
>  		dev_dbg(dev,
>  			"No interrupt pin definition, falling back to polling mode\n");

Kind regards,
Maarten

Re: [External Email] RE: [PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Andre Werner]

[-- Attachment #1: Type: text/plain, Size: 1438 bytes --]

Dear Maarten,

> > -----Original Message-----
> > Fix the IRQ check to treat the negative values as No IRQ.
>
> It seems to me that this is a real fix and needs a Fixes tag.
> See below.
>
> > Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
> > ---
> > diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> > index 7b51cdc274fd..560f45ed19ae 100644
> > --- a/drivers/tty/serial/sc16is7xx.c
> > +++ b/drivers/tty/serial/sc16is7xx.c
> > @@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct
> > sc16is7xx_devtype *devtype,
> >  	/* Always ask for fixed clock rate from a property. */
> >  	device_property_read_u32(dev, "clock-frequency", &uartclk);
> >
> > -	s->polling = !!irq;
> > +	s->polling = (irq <= 0);
>
> When irq>=0 these two lines above have a different outcome!
> irq==0   =>   !!irq==false   <=>   (irq<=0)==true
> irq==1   =>   !!irq==true   <=>   (irq<=0)==false

Thanks for the advice. I have not seen this all the time I looked at the
code. I accidentally forget to delete the second '!' as I did with the code
tested at the embedded device. Thanks for the advice.

Should I need to submit this patch again with a Fixup prefix or what needs
to be done?

>
> >  	if (s->polling)
> >  		dev_dbg(dev,
> >  			"No interrupt pin definition, falling back to polling mode\n");
>
> Kind regards,
> Maarten
>

Regards,
André

Re: [External Email] Re: [PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Andre Werner]

[-- Attachment #1: Type: text/plain, Size: 1507 bytes --]

Dear Greg,

> On Fri, Jan 17, 2025 at 06:18:22PM +0100, Andre Werner wrote:
> > Fix the IRQ check to treat the negative values as No IRQ.
> >
> > Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
> > ---
> > V2:
> > There are no changes to the patch itself. The previous patch submission
> > had a very weird structure within the discussion thread:
> > https://lkml.org/lkml/2025/1/16/398
> > This is simply a new thread opened for better handling.
> > ---
> >  drivers/tty/serial/sc16is7xx.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> > index 7b51cdc274fd..560f45ed19ae 100644
> > --- a/drivers/tty/serial/sc16is7xx.c
> > +++ b/drivers/tty/serial/sc16is7xx.c
> > @@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
> >  	/* Always ask for fixed clock rate from a property. */
> >  	device_property_read_u32(dev, "clock-frequency", &uartclk);
> >
> > -	s->polling = !!irq;
> > +	s->polling = (irq <= 0);
> >  	if (s->polling)
> >  		dev_dbg(dev,
> >  			"No interrupt pin definition, falling back to polling mode\n");
> > --
> > 2.48.0
> >
> >
>
> What commit id does this "fix"?

104c1b9dde9d859dd01bd2d71a2755a2fae43e15

https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git/commit/?h=tty-next&id=104c1b9dde9d859dd01bd2d71a2755a2fae43e15

>
> thanks,
>
> greg k-h
>

Regards,
André

Re: [External Email] Re: [PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Greg KH]

On Sat, Jan 18, 2025 at 08:28:49PM +0100, Andre Werner wrote:
> Dear Greg,
> 
> > On Fri, Jan 17, 2025 at 06:18:22PM +0100, Andre Werner wrote:
> > > Fix the IRQ check to treat the negative values as No IRQ.
> > >
> > > Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
> > > ---
> > > V2:
> > > There are no changes to the patch itself. The previous patch submission
> > > had a very weird structure within the discussion thread:
> > > https://lkml.org/lkml/2025/1/16/398
> > > This is simply a new thread opened for better handling.
> > > ---
> > >  drivers/tty/serial/sc16is7xx.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> > > index 7b51cdc274fd..560f45ed19ae 100644
> > > --- a/drivers/tty/serial/sc16is7xx.c
> > > +++ b/drivers/tty/serial/sc16is7xx.c
> > > @@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype,
> > >  	/* Always ask for fixed clock rate from a property. */
> > >  	device_property_read_u32(dev, "clock-frequency", &uartclk);
> > >
> > > -	s->polling = !!irq;
> > > +	s->polling = (irq <= 0);
> > >  	if (s->polling)
> > >  		dev_dbg(dev,
> > >  			"No interrupt pin definition, falling back to polling mode\n");
> > > --
> > > 2.48.0
> > >
> > >
> >
> > What commit id does this "fix"?
> 
> 104c1b9dde9d859dd01bd2d71a2755a2fae43e15
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git/commit/?h=tty-next&id=104c1b9dde9d859dd01bd2d71a2755a2fae43e15
> 

Great, then properly document that with a Fixes: tag when you resend
this please.

thanks,

greg k-h

Re: [External Email] RE: [PATCH v2] serial: sc16is7xx: Extend IRQ check for negative values

[Jiri Slaby]

On 18. 01. 25, 18:20, Andre Werner wrote:
> Dear Maarten,
> 
>>> -----Original Message-----
>>> Fix the IRQ check to treat the negative values as No IRQ.
>>
>> It seems to me that this is a real fix and needs a Fixes tag.
>> See below.
>>
>>> Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
>>> ---
>>> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
>>> index 7b51cdc274fd..560f45ed19ae 100644
>>> --- a/drivers/tty/serial/sc16is7xx.c
>>> +++ b/drivers/tty/serial/sc16is7xx.c
>>> @@ -1561,7 +1561,7 @@ int sc16is7xx_probe(struct device *dev, const struct
>>> sc16is7xx_devtype *devtype,
>>>   	/* Always ask for fixed clock rate from a property. */
>>>   	device_property_read_u32(dev, "clock-frequency", &uartclk);
>>>
>>> -	s->polling = !!irq;
>>> +	s->polling = (irq <= 0);
>>
>> When irq>=0 these two lines above have a different outcome!
>> irq==0   =>   !!irq==false   <=>   (irq<=0)==true
>> irq==1   =>   !!irq==true   <=>   (irq<=0)==false
> 
> Thanks for the advice. I have not seen this all the time I looked at the
> code. I accidentally forget to delete the second '!' as I did with the code
> tested at the embedded device. Thanks for the advice.
> 
> Should I need to submit this patch again with a Fixup prefix or what needs
> to be done?

Resubmit with complete description on what is broken and when. Incl. the 
Fixes: tag. The comment from Maarten suggests that it is broken in a 
completely different way than you describe in the commit log.

thanks,
-- 
js
suse labs