On Fri, Dec 10, 2021 at 07:38:40PM +0300, Sergey Shtylyov wrote:

On 12/10/21 11:47 AM, Andy Shevchenko wrote:

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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;

   -ENXIO seems to me more fitting indeed (than -EINVAL that I used).

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No, this is wrong for the same reasons I explained to Sergey.

   I fail to understand you, sorry. We're going in circles, it seems... :-/

platform_get_irq_optional() is supposed to return 0 when there is no IRQ found,
but everything else went alright.

I'm tired to waste my time to go circles.

Again, the problem is that platform_get_irq_optional() has wrong set of output
values. And your patch doesn't fix that. And it has nothing to do with my code
here.

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The problem is that this is _optional API and it has been misdesigned.
Replacing things like above will increase the mess.

   What's wrong with replacing IRQ0 with -ENXIO now? platform_get_irq_optional()
(as in your patch) could then happily return 0 ISO -ENXIO. Contrarywise, if we don't
replace IRQ0 with -ENXIO, platform_get_irq_optional() will return 0 for both IRQ0
and missing IRQ! Am I clear enough? If you don't understand me now, I don't know what
to say... :-/

See above. Read my messages again, please. I'm really tired to explain again
and again the same.

TL;DR: You simply try to "fix" in a correct place but in a wrong way.

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        return ret;

Otherwise, I do not think that removing the "if (!irq)" hunk is safe. no ?

No. This is not a business of the caller to workaround implementation
details (bugs) of the core APIs.
If something goes wrong, then it's platform_get_irq() to blame, and
not the libahci_platform.

   I'm repeating myself already: we don't work around the bug in platform_get_irq(),

Yes, you do.

we're working around the driver subsystems that treat 0 specially (and so don't
support IRQ0); libata treats 0 as an indication of the polling mode (moreover,
it will curse if you pass to it both IRQ == 0 and a pointer to an interrupt handler!
Am I clear enough this time? :-)

Yes, and it doesn't contradict to what my patch does.
Read comment against platform_get_irq(). If it returns 0,
it's not a business of the callers to work around it.

Am I clear enough this time? :-)

-- 
With Best Regards,
Andy Shevchenko