LayerscapeのトピックRe: Invalid rcw SYSCLK_FREQ value?

Invalid rcw SYSCLK_FREQ value?

zalbassam — Fri, 07 Apr 2017 18:45:17 GMT

Hi,

Im confused about the SYSCLK_FREQ rcw value on the LS1012ARDB. The rcw source is QSPI as the PORSR1 register says.

The "RCW field description" section in the LS1012 RM says the SYSCLK_FREQ value must be 0x258, so that the system clock is 100Mhz (0x258 * 166.667). However on my board the rcw SYSCLK_FREQ shows as 0x96. The RCW is never modified since the board was received.

Now my question, is the value 0x96 for SYSCLK_FREQ on the LS1012A valid? does that mean the SYSCLK is 0x96 * 166.667 = 25 Mhz?

Here is the RCW dump from uboot on my LS1012ARDB:

Clock Configuration:
CPU0(A53):800 MHz
Bus: 250 MHz DDR: 1000 MT/s
Reset Configuration Word (RCW):
00000000: 08000008 00000000 00000000 00000000
00000010: 35080000 c000000c 40000000 00001800
00000020: 00000000 00000000 00000000 000147f1
00000030: 00000000 18c2a120 00000096 00000000

Thanks,

Re: Invalid rcw SYSCLK_FREQ value?

ufedor — Sat, 08 Apr 2017 02:34:53 GMT

From the provided log:
00000000: 08000008 00000000 00000000 00000000
00000010: 35080000 c000000c 40000000 00001800

00000020: 00000000 00000000 00000000 000147f1

00000030: 00000000 18c2a120 00000096 00000000
The RCW[SYSCLK_FREQ] (10 bits) is contained in two words:

00000096	00000000
8 bits in this word	2 bits in this word

Binary representation:

8bits	2bits
1001_0110	00

Complete 10-bit field: 10_0101_1000

Re: Invalid rcw SYSCLK_FREQ value?

zalbassam — Sat, 08 Apr 2017 13:28:12 GMT

Now it makes sense. Thanks for the help!