linux-kernel - Re: [PATCH 2/2]: Be stric clocksource/drivers/fttmr010 on IRQs

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Message-ID: <cc934baf-75a9-d7f6-44ac-e7fa1c6f69b6@kaod.org>
Date:   Mon, 30 Aug 2021 09:47:01 +0200
From:   Cédric Le Goater <clg@...d.org>
To:     Guenter Roeck <linux@...ck-us.net>,
        Andrew Jeffery <andrew@...id.au>,
        Linus Walleij <linus.walleij@...aro.org>
CC:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Joel Stanley <joel@....id.au>
Subject: Re: [PATCH 2/2]: Be stric clocksource/drivers/fttmr010 on IRQs

On 8/30/21 6:58 AM, Guenter Roeck wrote:
> On 8/29/21 9:16 PM, Andrew Jeffery wrote:
> [ ... ]
>>>
>>>> I don't have the manuals, so I can't say what the correct behavior is,
>>>> but at least there is some evidence that TIMER_INTR_STATE may not exist
>>>> on ast2400 and ast2500 SOCs.
>>>
>>> On Aspeed SoCs AST2400 and AST2500, the TMC[34] register is a
>>> "control register #2" whereas on the AST2600 it is an "interruptarch/arm/boot/dts/ast2600-facebook-netbmc-common.dtsi:#include
>>> status register" with bits [0-7] holding the timers status.
>>>
>>> I would say that the patch simply should handle the "is_aspeed" case.
>>
>> Well, is_aspeed is set true in the driver for all of the 2400, 2500 and
>> 2600. 0x34 behaves the way this patch expects on the 2600. So I think
>> we need something less coarse than is_aspeed?
>>
> 
> If I understand the code correctly, ast2400 and ast2500 execute
> fttmr010_timer_interrupt(), while ast2600 has its own interrupt handler.
> To make this work, it would probably be necessary to check for is_aspeed
> in fttmr010_timer_interrupt(), and only execute the new code if the flag
> is false. The existing flag in struct fttmr010 should be good enough
> for that.

yes. 

I wonder why we have ast2600 support in fttmr010. The AST2600 boards use 
the arm_arch_timer AFAICT.

C.