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

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Date:   Thu, 18 May 2017 14:43:27 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Joel Stanley <joel@....id.au>
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" 
        <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>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Ryan Chen <ryan_chen@...eedtech.com>,
        Cédric Le Goater <clg@...d.org>
Subject: Re: [PATCH 7/8] clocksource/drivers/fttmr010: Merge Moxa into FTTMR010

On Thu, May 18, 2017 at 9:22 AM, Joel Stanley <joel@....id.au> wrote:
> On Wed, May 17, 2017 at 10:05 PM, 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.
>
> Nice work!
>
> I gave this a spin on hardware and it didn't work :(

How typical.

> Thanks for the rework! Unfortunately the Aspeed IP does not have bits
> to control the direction of counting, and the timers only count down.
> Bits 3, 7 and 11 are marked reserved in the data sheet. Can you rework
> the patch to count down?

How unintuitive.

I guess I will just make it handle the Aspeed separately, so we
count up on Gemini and Moxa and down on Aspeed if that is all
it can do.

> As an aside, we have a pretty decent model for the Aspeed SoCs in
> Qemu. If you want to use it to smoketest your rework:
>
>  $ qemu-system-arm -m 512 -M ast2500-evb -nodefaults -nographic
> -serial stdio -kernel arch/arm/boot/zImage -dtb
> arch/arm/boot/dts/aspeed-ast2500-evb.dtb
>
> I tested with Ubuntu's qemu v2.8. It looks like we have a bug when the
> kernel tries to use the clock the way your driver works, so we will
> look at that. It does function properly for the current upstream code.

Oh that's sweet! I'll test it if I can get it working like this.

Yours,
Linus Walleij