[PATCH 01/10 v4] Input: ep93xx_keypad: Fix platform_get_irq's error checking

[PATCH 01/10 v4] Input: ep93xx_keypad: Fix platform_get_irq's error checking

[Arvind Yadav]

The platform_get_irq() function returns negative if an error occurs.
zero or positive number on success. platform_get_irq() error checking
for zero is not correct.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
---
changes in v2 :
              Return keypad->irq insted of -ENXIO.
changes in v3 :
              Add failure case '<= 0' instead of '< 0'. IRQ0 is not valid.
changes ib v4 :
              Return -ENXIO insted of keypad->irq. Which was not correct in v3.

 drivers/input/keyboard/ep93xx_keypad.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/ep93xx_keypad.c b/drivers/input/keyboard/ep93xx_keypad.c
index f77b295..c6eb31a 100644
--- a/drivers/input/keyboard/ep93xx_keypad.c
+++ b/drivers/input/keyboard/ep93xx_keypad.c
@@ -257,7 +257,7 @@ static int ep93xx_keypad_probe(struct platform_device *pdev)
 	}
 
 	keypad->irq = platform_get_irq(pdev, 0);
-	if (!keypad->irq) {
+	if (keypad->irq <= 0) {
 		err = -ENXIO;
 		goto failed_free;
 	}
-- 
2.7.4

[PATCH 01/10 v4] Input: ep93xx_keypad: Fix platform_get_irq's error checking

[Russell King - ARM Linux]

On Mon, Nov 20, 2017 at 09:56:21PM +0530, Arvind Yadav wrote:
> The platform_get_irq() function returns negative if an error occurs.
> zero or positive number on success. platform_get_irq() error checking
> for zero is not correct.
> 
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> ---
> changes in v2 :
>               Return keypad->irq insted of -ENXIO.
> changes in v3 :
>               Add failure case '<= 0' instead of '< 0'. IRQ0 is not valid.
> changes ib v4 :
>               Return -ENXIO insted of keypad->irq. Which was not correct in v3.
> 
>  drivers/input/keyboard/ep93xx_keypad.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/keyboard/ep93xx_keypad.c b/drivers/input/keyboard/ep93xx_keypad.c
> index f77b295..c6eb31a 100644
> --- a/drivers/input/keyboard/ep93xx_keypad.c
> +++ b/drivers/input/keyboard/ep93xx_keypad.c
> @@ -257,7 +257,7 @@ static int ep93xx_keypad_probe(struct platform_device *pdev)
>  	}
>  
>  	keypad->irq = platform_get_irq(pdev, 0);
> -	if (!keypad->irq) {
> +	if (keypad->irq <= 0) {
>  		err = -ENXIO;

Still not right.

		err = keypad->irq < 0 ? keypad->irq : -ENXIO;

would have the right effect.

However, I disagree with the idea of making platform_get_irq() return
an error if there is a zero irq specified as suggested in a previous
review - zero means "not present" and that is not necessarily an error -
it's up to the driver to decide whether it can proceed without an
interrupt, or whether it should error out on the probe function.

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[PATCH 01/10 v4] Input: ep93xx_keypad: Fix platform_get_irq's error checking

[Dmitry Torokhov]

On Mon, Nov 20, 2017 at 8:29 AM, Russell King - ARM Linux
<linux@armlinux.org.uk> wrote:
> On Mon, Nov 20, 2017 at 09:56:21PM +0530, Arvind Yadav wrote:
>> The platform_get_irq() function returns negative if an error occurs.
>> zero or positive number on success. platform_get_irq() error checking
>> for zero is not correct.
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
>> ---
>> changes in v2 :
>>               Return keypad->irq insted of -ENXIO.
>> changes in v3 :
>>               Add failure case '<= 0' instead of '< 0'. IRQ0 is not valid.
>> changes ib v4 :
>>               Return -ENXIO insted of keypad->irq. Which was not correct in v3.
>>
>>  drivers/input/keyboard/ep93xx_keypad.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/input/keyboard/ep93xx_keypad.c b/drivers/input/keyboard/ep93xx_keypad.c
>> index f77b295..c6eb31a 100644
>> --- a/drivers/input/keyboard/ep93xx_keypad.c
>> +++ b/drivers/input/keyboard/ep93xx_keypad.c
>> @@ -257,7 +257,7 @@ static int ep93xx_keypad_probe(struct platform_device *pdev)
>>       }
>>
>>       keypad->irq = platform_get_irq(pdev, 0);
>> -     if (!keypad->irq) {
>> +     if (keypad->irq <= 0) {
>>               err = -ENXIO;
>
> Still not right.
>
>                 err = keypad->irq < 0 ? keypad->irq : -ENXIO;
>
> would have the right effect.
>
> However, I disagree with the idea of making platform_get_irq() return
> an error if there is a zero irq specified as suggested in a previous
> review - zero means "not present" and that is not necessarily an error -
> it's up to the driver to decide whether it can proceed without an
> interrupt, or whether it should error out on the probe function.

We used to return 0 from platform_get_irq() in early 2.6 days on
errors but not anymore and I do not think keeping treating 0 there as
special makes much sense.

We already return -ENXIO for missing resources, and I do not think
that anyone actually defines IRQ resource with 0 number and attaches
it to devices in home that drivers would recognize it as missing
interrupt and work without it. Also, in case of DT we do not recognize
IRQ 0 as valid and try to fetch it from other sources (static board
data), I think ACPI is similar.

I think we should also return -ENXIO in case of res->start == 0 and
leave it to the driver to check and decide if it wants to deal with
missing interrupt. Most of them do not.


Thanks.

-- 
Dmitry