OFW doesn't support operation at 1 and 1.2 GHZ on XO-4

[wad]

Quanta keeps requesting support for running the main cores at 1 GHz on XO-4. Currently they run at 800 MHz on XO-4 A2 motherboards.

I'm told that this requires firing up the second PLL, as the processors will no longer be synchronous to the memory interface.

As with XO-1.75, we have a GPIO (#3, w. jumpers on the motherboard) which should select the processor frequency (0 for 1 GHz, 1 for 1.2 GHz).

Quanta will have A2 boards with 1.2 GHz processors for testing by the end of next week (8/30/2012).

[Quozl]

Progress report:

• a PLL2 control register has moved from MMP2 (0x414) to MMP3 (0x418), so the banner display in Q7A08, which is coded for MMP2, is ignorant of the core frequency and should be ignored,
• we need fuses documentation to determine what the silicon supports, ticket 472527 relates, existing .fuses commandin Q7A08 is not valid and should be ignored,
• a recipe for switching to 1.063 GHz has been prepared from the documentation, but it doesn't yet work, further experimentation is required,
• in Q7A08, using .speed shows that pj4-910mhz and pj4-988mhz slows the core considerably over the default pj4-800mhz, so these also should be ignored,

[wmb@…]

Operation at 1.063 GHz is now working. There may be voltage setting changes necessary before it is stable - we have a report that 1.063 GHz is unstable if the L2 cache is on.

[wad]

Boards with 1.2GHz processors on them are now awaiting testing at QCI

[Quozl]

XO-4 with 1.2 GHz processor shows as 14xx MHz in Open Firmware banner. The calculation has lagged the CForth change. Not quite sure how pj4-speed needs to change.

[Quozl]

Was fixed.