Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved

Damien Le Moal
2021-12-10T23:45:59Z

On 2021/12/10 17:59, Sergey Shtylyov wrote:
> On 12/10/21 1:49 AM, Damien Le Moal wrote:
>
>>> platform_get_irq() will print a message when it fails.
>>> No need to repeat this.
>>>
>>> While at it, drop redundant check for 0 as platform_get_irq() spills
>>> out a big WARN() in such case.
>>
>> The reason you should be able to remove the "if (!irq)" test is that
>> platform_get_irq() never returns 0. At least, that is what the function kdoc
>> says. But looking at platform_get_irq_optional(), which is called by
>> platform_get_irq(), the out label is:
>>
>> WARN(ret == 0, "0 is an invalid IRQ number\n");
>> return ret;
>>
>> So 0 will be returned as-is. That is rather weird. That should be fixed to
>> return -ENXIO:
>>
>> if (WARN(ret == 0, "0 is an invalid IRQ number\n"))
>> return -ENXIO;
>> return ret;
>
> My unmerged patch (https://marc.info/?l=linux-kernel&m=163623041902285) does this
> but returns -EINVAL instead.

Thinking more about this, shouldn't this change go into platform_get_irq()
instead of platform_get_irq_optional() ?

The way I see it, I think that the intended behavior for
platform_get_irq_optional() is:
1) If have IRQ, return it, always > 0
2) If no IRQ, return 0
3) If error, return < 0
no ?

And for platform_get_irq(), case (2) becomes an error.
Is this the intended semantic ?
I am really not sure here as the functions kdoc description and the code do not
match. Which one is correct ?

>
>> Otherwise, I do not think that removing the "if (!irq)" hunk is safe. no ?
>
> Of course it isn't...
>
>>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> [...]
>
> MBR, Sergey

--
Damien Le Moal
Western Digital Research