linux-kernel - Re: [PATCH v3 05/25] clocksource: owl: Add S900 support

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Date:   Tue, 28 Feb 2017 18:16:10 +0100
From:   Andreas Färber <afaerber@...e.de>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     arm@...nel.org, support@...aker.org, linux-kernel@...r.kernel.org,
        mp-cs@...ions-semi.com, 96boards@...obotics.com,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 05/25] clocksource: owl: Add S900 support

Daniel,

Am 28.02.2017 um 07:35 schrieb Andreas Färber:
> The Actions Semi S900 SoC provides four 32-bit timers, TIMER0/1/2/3,
> but no 2Hz timers.
> 
> Deal with the S500 having less timers.
> 
> An S900 datasheet can be found in 96Boards documentation:
> https://github.com/96boards/documentation/blob/master/ConsumerEdition/Bubblegum-96/HardwareDocs/SoC_bubblegum96.pdf
> 
> Signed-off-by: Andreas Färber <afaerber@...e.de>
[...]
> @@ -126,10 +127,20 @@ static irqreturn_t owl_timer1_interrupt(int irq, void *dev_id)
>  static const struct owl_timer_info s500_timer_info = {
>  	.timer_offset[0] = 0x08,
>  	.timer_offset[1] = 0x14,
> +	.timer_offset[2] = -1,
> +	.timer_offset[3] = -1,
> +};
> +
> +static const struct owl_timer_info s900_timer_info = {
> +	.timer_offset[0] = 0x08,
> +	.timer_offset[1] = 0x14,
> +	.timer_offset[2] = 0x30,
> +	.timer_offset[3] = 0x3c,
>  };

I noticed later that the S900 manual describes TIMER2/3 as "used only in
Secure mode". My driver code resetting them seems to work though.

Should we just drop these extra timer initializations then to make the
driver simpler and more performant again? I'd still like to keep the two
compatible strings in the DT though, and we may want to disable the 2Hz
timers on S500 just in case.

Regards,
Andreas

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