linux-kernel - Re: [PATCH 2/2]: Be stric clocksource/drivers/fttmr010ter on IRQs

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Message-ID: <f71cbfb9-b72c-39d2-6acb-dc83b6a496f8@roeck-us.net>
Date:   Sun, 29 Aug 2021 21:58:36 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Andrew Jeffery <andrew@...id.au>,
        Cédric Le Goater <clg@...d.org>,
        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/fttmr010ter on IRQs

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.

Guenter