On Sat, Dec 11, 2021 at 08:45:51AM +0900, Damien Le Moal wrote:

On 2021/12/10 17:59, Sergey Shtylyov wrote:

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On 12/10/21 1:49 AM, Damien Le Moal 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;
	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 ?

At least this is my understanding on how it _should_ be.

And for platform_get_irq(), case (2) becomes an error.

Precisely!

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 ?

The problem is that platform_get_irq_optional() doesn't follow above mentioned
logic and needs to be fixed. While trying to fix that it appears that it's not
an simple and 5 minutes task since it needs a revisiting of all callers first
followed by rectifying the API itself.

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

   Of course it isn't...

-- 
With Best Regards,
Andy Shevchenko