Linux: AM335x wrong clock initialization

Patrick Schmelzer

Prodigy 70 points

Other Parts Discussed in Thread: AM3358

Tool/software: Linux

We are using a customized board basically derived from the BeagleBone Black with the Sitara am3358 processor.

I figured out that it looks like that in 10% of the start-ups a wrong clock is initialized.

Due to some other problem, I was investigating the usleep delay which we are using in a kernel driver.

With the use of a logic analyzer I saw that a delay of 10ms is in 10% of the cases only around 6ms.

Are there multiple configurations colliding?

Thanks a lot for your help.

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

The ROM code reads the value of the main clock from the signals SYSBOOT[15:14], which are latched internally at power-on reset release time. You should check that these 2 signals are at valid levels at this time.

0 Patrick Schmelzer over 8 years ago in reply to Biser Gatchev-XID

Prodigy 70 points

I looked into the two signals and they look fine.
I continued investigated and I have the following output (always) in the kernel log.

0.000000] Build-time adjustment of leaf fanout to 32.
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] IRQ: Found an INTC at 0xfa200000 (revision 5.0) with 128 interrupts
[ 0.000000] OMAP clockevent source: timer2 at 24000000 Hz
[ 0.000019] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 89478484971ns
[ 0.000043] clocksource: timer1: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635851949 ns
[ 0.000056] OMAP clocksource: timer1 at 24000000 Hz
[ 0.002096] clocksource_probe: no matching clocksources found
[ 0.002392] Console: colour dummy device 80x30
[ 0.002427] Calibrating delay loop... 712.70 BogoMIPS (lpj=356352)

"no matching clocksources found"

Best regards,
Patrick

0 Biser Gatchev-XID over 8 years ago in reply to Patrick Schmelzer

TI__Guru**** 393215 points

What Linux version is this?

0 Patrick Schmelzer over 8 years ago in reply to Biser Gatchev-XID

Prodigy 70 points

Linux 4.9.50

0 Biser Gatchev-XID over 8 years ago in reply to Patrick Schmelzer

TI__Guru**** 393215 points

This is not the officially released AM335x Linux Processor SDK: www.ti.com/.../PROCESSOR-SDK-AM335X This forum supports only the Linux SDK released by TI.

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Linux: AM335x wrong clock initialization