On Mon, Jul 4, 2016 at 3:42 PM, Sudeep Holla <sudeep.ho...@arm.com> wrote: > > > On 04/07/16 14:17, Rafael J. Wysocki wrote: >> >> On Monday, July 04, 2016 02:00:03 PM Sudeep Holla wrote: >>> >>> >>> On 01/07/16 14:07, Daniel Lezcano wrote: >>>> >>>> On 06/28/2016 03:55 PM, Sudeep Holla wrote: >>>>> >>>>> ACPI 6.0 introduced an optional object _LPI that provides an alternate >>>>> method to describe Low Power Idle states. It defines the local power >>>>> states for each node in a hierarchical processor topology. The OSPM can >>>>> use _LPI object to select a local power state for each level of >>>>> processor >>>>> hierarchy in the system. They used to produce a composite power state >>>>> request that is presented to the platform by the OSPM. >>>>> >>>>> Since multiple processors affect the idle state for any non-leaf >>>>> hierarchy >>>>> node, coordination of idle state requests between the processors is >>>>> required. ACPI supports two different coordination schemes: Platform >>>>> coordinated and OS initiated. >>>>> >>>>> This patch adds initial support for Platform coordination scheme of >>>>> LPI. >>>>> >>>>> Cc: "Rafael J. Wysocki" <r...@rjwysocki.net> >>>>> Signed-off-by: Sudeep Holla <sudeep.ho...@arm.com> >>>>> --- >>>> >>>> >>>> Hi Sudeep, >>>> >>>> I looked at the acpi processor idle code sometime ago and from my POV, >>>> it was awful, unnecessary complex and very difficult to maintain. The >>>> usage of flags all over the places is significant of the lack of control >>>> of the written code. >>>> >>> >>> So you have any specific things in mind ? That's too broad and I know >>> it's not so clean, but it's so for legacy reasons. I would leave that >>> to Rafael to decide as it takes lots of testing to clean up these code. >> >> >> The cleanup needs to be done at one point. >> >> Question is when to do it, before adding LPI support or after doing that >> (and each option has its pros and cons IMO). >> >>>> Even if you are not responsible of this implementation, the current >>>> situation forces you to add more awful code on top of that, which is >>>> clearly against "making Linux better". >>>> >>> >>> OK >> >> >> So if there are cases in which you need to make the code more complex >> because of the legacy stuff in there, I'd say it's better to clean it up >> first. >> > > I am not sure if Daniel was referring to anything specific. I have > cleaned up in patch 1/6 for cstate. More cleanups can be done there but > needs better understanding and reasoning for the current code which I > don't have as they are mostly x86 related. > > Unless someone points me what they would like to change and how, I don't > have much in my mind to do here. Yes it may not look as clean as other > code in the kernel relatively, but without complete understanding of the > history/reasoning for the current state of code I wouldn't touch > anything I don't understand. > > I am open to make changes if there's something specific. Sorry I can't > go ahead making changes the way I think based on some vague idea that > the current code is not clean.
Fair enough.
