Power Management with AT91sam9260-EK

psa · **Posted:** Mon Jul 23, 2007 5:15 pm

Hi,

I try to compile linux 2.6.21+at91patch with the option : CONFIG_AT91_SLOW_CLOCK. But I have many errors in the file : pm_slowclock.S :

Code:

  AS      arch/arm/mach-at91/pm_slowclock.o
arch/arm/mach-at91/pm_slowclock.S: Assembler messages:
arch/arm/mach-at91/pm_slowclock.S:81: Error: address offset too large -- `ldr r2,[r1,#((0xfffffc00-0xffffc000)+0x30)]'
arch/arm/mach-at91/pm_slowclock.S:94: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x30)]'
arch/arm/mach-at91/pm_slowclock.S:96: Error: address offset too large -- `ldr r3,[r1,#((0xfffffc00-0xffffc000)+0x68)]'
arch/arm/mach-at91/pm_slowclock.S:99: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x30)]'
arch/arm/mach-at91/pm_slowclock.S:103: Error: address offset too large -- `ldr r2,[r1,#((0xfffffc00-0xffffc000)+0x28)]'
arch/arm/mach-at91/pm_slowclock.S:107: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x28)]'
arch/arm/mach-at91/pm_slowclock.S:109: Error: address offset too large -- `ldr r3,[r1,#((0xfffffc00-0xffffc000)+0x68)]'
arch/arm/mach-at91/pm_slowclock.S:113: Error: address offset too large -- `ldr r2,[r1,#((0xfffffc00-0xffffc000)+0x20)]'
arch/arm/mach-at91/pm_slowclock.S:115: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x20)]'
arch/arm/mach-at91/pm_slowclock.S:123: Error: address offset too large -- `ldr r2,[r1,#((0xfffffc00-0xffffc000)+0x20)]'
arch/arm/mach-at91/pm_slowclock.S:125: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x20)]'
arch/arm/mach-at91/pm_slowclock.S:127: Error: address offset too large -- `ldr r3,[r1,#((0xfffffc00-0xffffc000)+0x68)]'
arch/arm/mach-at91/pm_slowclock.S:132: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x28)]'
arch/arm/mach-at91/pm_slowclock.S:134: Error: address offset too large -- `ldr r3,[r1,#((0xfffffc00-0xffffc000)+0x68)]'
arch/arm/mach-at91/pm_slowclock.S:151: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x30)]'
arch/arm/mach-at91/pm_slowclock.S:153: Error: address offset too large -- `ldr r3,[r1,#((0xfffffc00-0xffffc000)+0x68)]'
arch/arm/mach-at91/pm_slowclock.S:156: Error: address offset too large -- `str r2,[r1,#((0xfffffc00-0xffffc000)+0x30)]'
arch/arm/mach-at91/pm_slowclock.S:158: Error: address offset too large -- `ldr r3,[r1,#((0xfffffc00-0xffffc000)+0x68)]'
make[1]: *** [arch/arm/mach-at91/pm_slowclock.o] Error 1
make: *** [arch/arm/mach-at91] Error 2

Somebody have already see this error ???

Could you help me ???

Thanks in advance.

Pierre

AntiSullin · **Posted:** Thu Aug 09, 2007 10:56 am

PM is only implemented for AT91RM9200 and it does not work for others. The SAM926x is a bit different. I've ported the PM to SAM9261, but it isn't finished yet. On one kind of devices, the device crashes when coming back from suspend in about every 3000th time done. As it is ready, Ill post the patch here, too.

psa · **Posted:** Thu Aug 09, 2007 1:12 pm

Currently I manage to regulate the frequency of the processor with CKGR_PLLAR and PMC_MCKR. However when I put a frequency different from 100 MHz for MCK I cannot use the console any more.
What do I have to make to keep the console?

Thanks in advance

AntiSullin · **Posted:** Fri Aug 10, 2007 12:43 pm

You cannot change the system clock frequency on the fly. At least, when the system is running. The PM driver lowers the clocks to 32kHz only on suspend and on resume, reconfigures enerything back to where it was before. A lot of timers and clocks depend on the system clock, including the serial output clock and SDRAM clock. When changing the system clock on-the-fly, everything needs to be re-calculated and currently, there are no interfaces to do that.
So, lowering the clock speed is currently only possible for standby and it needs to be reset when coming back.

joysarba · **Joined:** Wed Nov 01, 2006 6:09 pm **Posts:** 13

Hi Antisullin,

Was just checking if you managed to get standby/resume running on any of the sam926x microcontrollers. Am trying to port it but for some reason when the core comes out of standby, it seems to hang. Will keep researching this but any tips in the meanwhile would be helpful.

Thanks,
Joy.

Power Management with AT91sam9260-EK

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