linux-kernel - Re: [PATCH 1/2] clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue

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Date:   Mon, 22 Mar 2021 16:55:31 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Tony Lindgren <tony@...mide.com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Keerthy <j-keerthy@...com>, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Tero Kristo <kristo@...nel.org>
Subject: Re: [PATCH 1/2] clocksource/drivers/timer-ti-dm: Prepare to handle
 dra7 timer wrap issue

On 04/03/2021 08:37, Tony Lindgren wrote:
> There is a timer wrap issue on dra7 for the ARM architected timer.
> In a typical clock configuration the timer fails to wrap after 388 days.
> 
> To work around the issue, we need to use timer-ti-dm timers instead.
> 
> Let's prepare for adding support for percpu timers by adding a common
> dmtimer_clkevt_init_common() and call it from dmtimer_clockevent_init().
> This patch makes no intentional functional changes.
> 
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> ---

[ ... ]

> @@ -575,33 +574,60 @@ static int __init dmtimer_clockevent_init(struct device_node *np)
>  	 */
>  	writel_relaxed(OMAP_TIMER_CTRL_POSTED, t->base + t->ifctrl);
>  
> +	if (dev->cpumask == cpu_possible_mask)
> +		irqflags = IRQF_TIMER;
> +	else
> +		irqflags = IRQF_TIMER | IRQF_NOBALANCING;

Can you explain the reasoning behind the test above ?

[ ... ]


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