From mboxrd@z Thu Jan  1 00:00:00 1970
From: York Sun <yorksun@freescale.com>
Date: Thu, 19 Mar 2015 11:24:10 -0700
Subject: [U-Boot] [PATCH 04/28] armv8/ls2085a: Fix generic timer clock
 source
In-Reply-To: <20150319181752.GI10153@leverpostej>
References: <1426783559-26610-1-git-send-email-yorksun@freescale.com>
 <1426783559-26610-4-git-send-email-yorksun@freescale.com>
 <20150319180857.GG10153@leverpostej> <550B1279.4060507@freescale.com>
 <20150319181752.GI10153@leverpostej>
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On 03/19/2015 11:17 AM, Mark Rutland wrote:
> On Thu, Mar 19, 2015 at 06:16:25PM +0000, York Sun wrote:
>> On 03/19/2015 11:08 AM, Mark Rutland wrote:
>>>> +
>>>> +int timer_init(void)
>>>> +{
>>>> +	u32 __iomem *cntcr = (u32 *)CONFIG_SYS_FSL_TIMER_ADDR;
>>>> +	u32 __iomem *cltbenr = (u32 *)CONFIG_SYS_FSL_PMU_CLTBENR;
>>>> +#ifdef COUNTER_FREQUENCY_REAL
>>>> +	unsigned long cntfrq = COUNTER_FREQUENCY_REAL;
>>>> +
>>>> +	/* Update with accurate clock frequency */
>>>> +	asm volatile("msr cntfrq_el0, %0" : : "r" (cntfrq) : "memory");
>>>> +#endif
>>>
>>> Is this executed on all CPUs, or do secondary CPUs have CNTFRQ
>>> programmed with the correct value elsewhere?
>>>
>>
>> Only the primary CPU runs here. The secondary CPU doesn't come here.
> 
> Ok. Where does CNTFRQ get programmed for those CPUs?
> 
> If it's necessary to write COUNTER_FREQUENCY_REAL to the primary CPU's
> CNTFRQ, that's also necessary on the secondaries before they enter the
> OS.

Hmm, this may be a bug. Didn't hear any complain from Linux users. We found the
timer wasn't correct during bring-up. Let me check with internal team.

Thanks, Mark.

York