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Date: Fri, 28 Nov 2014 14:35:32 +0000
From: Mark Rutland <mark.rutland@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
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Subject: Re: [PATCH v3 3/5] arm64: dts: Add support for Spreadtrum SC9836 SoC
 in dts and Makefile
Message-ID: <20141128143532.GI25883@leverpostej>
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On Fri, Nov 28, 2014 at 02:29:13PM +0000, Catalin Marinas wrote:
> On Thu, Nov 27, 2014 at 01:43:09PM +0000, Mark Rutland wrote:
> > On Thu, Nov 27, 2014 at 12:12:15PM +0000, Catalin Marinas wrote:
> > > On Thu, Nov 27, 2014 at 11:50:43AM +0000, Mark Rutland wrote:
> > > > On Tue, Nov 25, 2014 at 12:16:56PM +0000, Chunyan Zhang wrote:
> > > > > +
> > > > > +       timer {
> > > > > +               compatible = "arm,armv8-timer";
> > > > > +               interrupts = <1 13 0xff01>,
> > > > > +                            <1 14 0xff01>,
> > > > > +                            <1 11 0xff01>,
> > > > > +                            <1 10 0xff01>;
> > > > > +               clock-frequency = <26000000>;
> > > > 
> > > > Please remove the clock-frequency property. Your FW should initialise
> > > > CNTFRQ_EL0 on all CPUs (certainly PSCI 0.2 requires that you do this).
> > > 
> > > Since this comes up regularly, I think we need a dev_warn() in the arch
> > > timer driver when CONFIG_ARM64.
> > 
> > I'll ack such a patch ;)
> 
> How rude would this be?
> 
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 2133f9d59d06..aaaf3433ccb9 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -371,7 +371,8 @@ arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np)
> 		return;
>  
> 	/* Try to determine the frequency from the device tree or CNTFRQ */
> -	if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
> +	if (IS_ENABLED(CONFIG_ARM64) ||
> +	    of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
> 		if (cntbase)
> 			arch_timer_rate = readl_relaxed(cntbase + CNTFRQ);
> 		else
>

Probably too rude, given it doesn't WARN() the user.

We should be extremely loud if we see the clock-frequency property on an
arm64 system. Whether or not we should ignore the property is another
matter.

Mark.
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