linux-kernel - Re: [PATCH 3/6] cpuidle: menu: Get rid of first_idx from menu

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Message-ID: <CAJZ5v0iysZaRY92ocQisAM3jaRUzoaQYrsbGXs4WwntEKMbLCQ@mail.gmail.com>
Date:   Fri, 5 Oct 2018 10:49:40 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/6] cpuidle: menu: Get rid of first_idx from menu_select()

On Fri, Oct 5, 2018 at 10:35 AM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> On 04/10/2018 19:19, Rafael J. Wysocki wrote:
> > On Thu, Oct 4, 2018 at 4:51 PM Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
> >>
> >> On Tue, Oct 02, 2018 at 11:44:06PM +0200, Rafael J. Wysocki wrote:
> >>> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >>>
> >>> Rearrange the code in menu_select() so that the loop over idle states
> >>> always starts from 0 and get rid of the first_idx variable.
> >>>
> >>> While at it, add two empty lines to separate conditional statements
> >>> one another.
> >>>
> >>> No intentional behavior changes.
> >>>
> >>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >>> ---
> >>
> >> This code is becoming a bit complex to follow :/
> >>
> >> May be I missed something, but it is not possible to enter the condition without
> >> idx != 0, no ? (I meant the condition if ((drv->states[idx].flags &
> >> FLAG_POLLING))
> >
> > Not sure what you mean.
>
> Yes, sorry let me clarify.
>
> I meant the flag polling is always on state[0], so if the flag is set
> then idx == 0.
>
> We have the conditions:
>
>   drv->states[idx].flags & CPUIDLE_FLAG_POLLING
>
> If it is true then idx is zero.
>
>
> Then comes the second condition:
>
>   i == idx + 1
>
> because of the above, idx is zero, then it can become i == 1.
>
> Then the variable assignation:
>
>  idx = i can be replaced by idx = 1

Yes, but the former works too. :-)