RE: [U-Boot-Users] AT91RM9200 Errata (Was: CSB637 support - big bug..)

Hi,
Anders Larsen wrote on :
"Patrick .." oc3an@gmx.net schreibt:
Also, it is safe to use a divisor of 3 for the Master Clock, this gives 61.44MHz from a core of 184.32Mhz which is fine for the CSB637 (master clock limit is 80MHz), users should see a decent improvement in performance by doing this as it will increase the SDRAM bandwidth by a substantial amount.
Well, I got the clock values from linux 2.6.12 board-csb637.c; does Linux still boot correctly with your change?
I already posted this on the list, but a little reminder won't hurt :)
A clock rate > 180 MHz could be problematic. According errata 42 (AC Characteristics: PLL Frequency Limitation), in AT91RM9200 errata sheet (doc6015) the PLL is limited to 180 MHz. We already had problems with this bug (with about 10%-15% of the CPUs). After configuring the PLL for 179 MHz no errors occour any mor (before we used 207 MHz).
Regards, Martin

Martin,
A clock rate > 180 MHz could be problematic. According errata 42 (AC Characteristics: PLL Frequency Limitation), in AT91RM9200 errata sheet (doc6015) the PLL is limited to 180 MHz. We already had problems with this bug (with about 10%-15% of the CPUs). After configuring the PLL for 179 MHz no errors occour any mor (before we used 207 MHz).
Which errors and problems did you encounter?
-- Steven

"Martin Krause" Martin.Krause@tqs.de schreibt:
I already posted this on the list, but a little reminder won't hurt :)
A clock rate > 180 MHz could be problematic. According errata 42 (AC Characteristics: PLL Frequency Limitation), in AT91RM9200 errata sheet (doc6015) the PLL is limited to 180 MHz. We already had problems with this bug (with about 10%-15% of the CPUs). After configuring the PLL for 179 MHz no errors occour any mor (before we used 207 MHz).
Hi,
207 MHz is way beyond the limit - the 184 MHz of the CSB637 was specified by Cogent, so /they/ are responsible for selecting chips that can handle that frequency :-)
Cheers Anders
participants (3)
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Anders Larsen
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Martin Krause
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Steven Scholz