linux-kernel - Re: [PATCH] driver core: platform: Rename platform_get_irq_optional() to platform_get_irq

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Date:   Fri, 14 Jan 2022 20:55:07 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Mark Brown <broonie@...nel.org>
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Subject: Re: [PATCH] driver core: platform: Rename platform_get_irq_optional()
 to platform_get_irq_silent()

On 1/14/22 12:42 AM, Florian Fainelli wrote:

>> The subsystems regulator, clk and gpio have the concept of a dummy
>> resource. For regulator, clk and gpio there is a semantic difference
>> between the regular _get() function and the _get_optional() variant.
>> (One might return the dummy resource, the other won't. Unfortunately
>> which one implements which isn't the same for these three.) The
>> difference between platform_get_irq() and platform_get_irq_optional() is
>> only that the former might emit an error message and the later won't.
>>
>> To prevent people's expectations that there is a semantic difference
>> between these too, rename platform_get_irq_optional() to
>> platform_get_irq_silent() to make the actual difference more obvious.
>>
>> The #define for the old name can and should be removed once all patches
>> currently in flux still relying on platform_get_irq_optional() are
>> fixed.
>>
>> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
[...]
>>>> I think at least c) is easy to resolve because
>>>> platform_get_irq_optional() isn't that old yet and mechanically
>>>> replacing it by platform_get_irq_silent() should be easy and safe.
>>>> And this is orthogonal to the discussion if -ENOXIO is a sensible return
>>>> value and if it's as easy as it could be to work with errors on irq
>>>> lookups.
>>>
>>> It'd certainly be good to name anything that doesn't correspond to one
>>> of the existing semantics for the API (!) something different rather
>>> than adding yet another potentially overloaded meaning.
>>
>> It seems we're (at least) three who agree about this. Here is a patch
>> fixing the name.
> 
> From an API naming perspective this does not make much sense anymore with the name chosen,
> it is understood that whent he function is called platform_get_irq_optional(), optional applies
> to the IRQ. An optional IRQ is something people can reason about because it makes sense.

   Right! :-)

> What is a a "silent" IRQ however? It does not apply to the object it is trying to fetch to
> anymore, but to the message that may not be printed in case the resource failed to be obtained,
> because said resource is optional. Woah, that's quite a stretch.

   Right again! :-)

> Following the discussion and original 2 patches set from Sergey, it is not entirely clear to me
> anymore what is it that we are trying to fix.

   Andy and me tried to fix the platform_get_irq[_byname]_optional() value, corresponding to
a missing (optional) IRQ resource from -ENXIO to 0, in order to keep the callers error code
agnostic. This change completely aligns e.g. platform_get_irq_optional() with clk_get_optional()
and gpiod_get_optional()...
   Unforunately, we can't "fix" request_irq() and company to treat 0 as missing IRQ -- they have
to keep the ability to get called from the arch/ code (that doesn't use platform_get_irq(), etc.

> I nearly forgot, I would paint it blue, sky blue, not navy blue, not light blue ;)

   :-)

PS: Florian, something was wrong with your mail client -- I had to manually wrap your quotes,
else there were super long unbroken paragraphs...