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

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Message-ID: <20211059-ec50-4b9a-9625-e69d9971cb68@kernel.org>
Date: Sun, 19 Jan 2025 09:00:55 +0100
From: Jiri Slaby <jirislaby@...nel.org>
To: Andre Werner <andre.werner@...tec-electronic.com>,
 Maarten Brock <Maarten.Brock@...ls.nl>
Cc: "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
 "hvilleneuve@...onoff.com" <hvilleneuve@...onoff.com>,
 "andy@...nel.org" <andy@...nel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
 "lech.perczak@...lingroup.com" <lech.perczak@...lingroup.com>
Subject: Re: [External Email] RE: [PATCH v2] serial: sc16is7xx: Extend IRQ
 check for negative values

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@...tec-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