Re: [PATCH v3] ACPI / Processor: add sysfs support for low power idle

[Sudeep Holla <sudeep.holla@arm.com>]

On 15/11/17 15:33, Timur Tabi wrote:
> On Wed, Nov 8, 2017 at 8:18 AM, Sudeep Holla <sudeep.holla@arm.com> wrote:
>> I still prefer this as debugfs and not as sysfs ABI. We already have
>> issues with multiple interfaces for the same thing. E.g. cpufreq on x86.
>> I don't want this to end up in the same way after few years. CPUIdle
>> sysfs should be only sysfs ABI for these, adding an alternative is
>> inviting troubles for future especially if some user-space starts using
>> it and we will be stuck with that. Moreover with more h/w controlled
>> idle we may not provide accurate data sooner.
>>
>> Sorry for the noise, I will shup up now ;). Since this may be last
>> chance to make some noise, I am trying it. I completely understand that
>> this is just my opinion and am fine if others thinks it's good to make
>> this sysfs ABI.
> 
> Unfortunately, I think Prashanth really needs a specific requirement
> rather than opinions. 

I completely understand that. So for I haven't got a solid reason as
why debugfs is not sufficient? If it becomes so popular in future, we
can discuss and then make it sysfs ABI with more thoughts/discussions.

> This patch has been languishing for over a month, and we still have
> no idea whether it will make 4.15 or if Prashanth is *required* to
> make any more changes.
> 

It's sysfs ABI which we need to support for very long time(not in months
but in years), so waiting/discussing for couple of months is much safer
than spending more time to keep it the sysfs ABI unbroken.

Also I assume(was explicitly mentioned IIRC) that it's purely used
for debug and tuning purposes and hence I see *no need* to be part of
*sysfs ABI*. Let me know if the circumstances have changed.

-- 
Regards,
Sudeep