linux-kernel - Re: [PATCH 7/8 v2] clocksource/drivers/fttmr010: Merge Moxa into FTTMR010

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Date:   Fri, 19 May 2017 13:14:20 +0800
From:   Joel Stanley <joel@....id.au>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jonas Jensen <jonas.jensen@...il.com>,
        Janos Laube <janos.dev@...il.com>,
        Paulius Zaleckas <paulius.zaleckas@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Hans Ulli Kroll <ulli.kroll@...glemail.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Cédric Le Goater <clg@...d.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Andrew Jeffery <andrew@...id.au>
Subject: Re: [PATCH 7/8 v2] clocksource/drivers/fttmr010: Merge Moxa into FTTMR010

On Fri, May 19, 2017 at 4:17 AM, Linus Walleij <linus.walleij@...aro.org> wrote:
> This merges the Moxa Art timer driver into the Faraday FTTMR010
> driver and replaces all Kconfig symbols to use the Faraday
> driver instead. We are now so similar that the drivers can
> be merged by just adding a few lines to the Faraday timer.
>
> Differences:
>
> - The Faraday driver explicitly sets the counter to count
>   upwards for the clocksource, removing the need for the
>   clocksource core to invert the value.
>
> - The Faraday driver also handles sched_clock()
>
> On the Aspeed, the counter can only count downwards, so support
> the timers in downward-counting mode as well, and flag the
> Aspeed to use this mode. This mode was tested on the Gemini so
> I have high hopes that it'll work fine on the Aspeed as well.
>
> After this we have one driver for all three SoCs and a generic
> Faraday FTTMR010 timer driver, which is nice.
>
> Cc: Joel Stanley <joel@....id.au>
> Cc: Jonas Jensen <jonas.jensen@...il.com>
> Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
> ---
> ChangeLog v1->v2:
> - As it appears that the Aspeed timers can only count downwards,
>   augment the code to deal with downward counting clockevent,
>   clock source and sched_clock(), and flag the Aspeed for this
>   mode.
>
> ARM SoC folks: please ACK this so it can be merged with in the
> clocksource subsystem once it works.
>
> Joel: it would be super if you can test this. If you have some
> vendor tree or similar that actually indicates where the
> up/down counter bits are it's even better, but I'm hoping that
> this half-assed guesswork will JustWork(TM) (yeah, famous
> last words, sorry...)

I gave it a spin on the ast2500-evb and it worked for me.

I also gave it a read through and it looks good. I'd lowercase the
shouty FTTMR010-TIMER message that pops up during boot, but it's no
biggie.

Reviewed-by: Joel Stanley <joel@....id.au>
Tested-by: Joel Stanley <joel@....id.au>

Cheers,

Joel