linux-kernel - Re: [RFC] Improving udelay/ndelay on platforms where that is possible

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Message-ID: <e03436d1-b140-3f29-59a6-3b1eb6bf9da4@free.fr>
Date:   Wed, 1 Nov 2017 20:38:42 +0100
From:   Marc Gonzalez <marc_gonzalez@...madesigns.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        John Stultz <john.stultz@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        Nicolas Pitre <nico@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Will Deacon <will.deacon@....com>,
        Jonathan Austin <jonathan.austin@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Kevin Hilman <khilman@...nel.org>,
        Russell King <linux@....linux.org.uk>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>, Mason <slash.tmp@...e.fr>
Subject: Re: [RFC] Improving udelay/ndelay on platforms where that is possible

On 01/11/2017 20:09, Linus Torvalds wrote:

> On Wed, Nov 1, 2017 at 12:03 PM, Marc Gonzalez wrote:
>
>> By default, ndelay is implemented in terms of udelay.
> 
> That's very much *NOT* the case.
> 
> Yes, there is a *fallback* for when somebody doesn't do ndelay() at
> all, but that doesn't make it the default.
> 
> It's just a "the architecture didn't implement ndelay at all, we'll
> work around it".

Yes, sorry, I wrote "default" when I meant "fallback".
(arm32 currently does not define a specific ndelay implementation.)

> So stop this idiocy already. About half of what I've seen in this
> thread has been pure garbage.

OK, I'll just send my patch, and then crawl back under my rock.

Regards.