Hi all,
I made a patch for 2.6.36 kernel (git://git.kernel.org/pub/scm/linux/
kernel/git/tmlind/linux-omap-2.6.git) that makes it possible to run
Beagleboard-xM on 1 GHz frequency. The main idea is adjusting
processor voltage VDD1 to the level of OPP1G (1.28..1.38V). Please
note that default processor voltage after boot is 1.2V according to
BOOT0 (=1) and BOOT1 (=0) pins on TPS65950 (see "Table 5-2. Boot
Modes" in SWCU050F, p.238). You can see processor voltage values for
different frequencies in "Table 4-20. Processor Clocks" in SPRS685B
document (p.144). In order to increase voltage there are three
options:
1) SmartReflex technology (implemented in kernel 2.6.32 from Arago,
also used in TI VDSDK and Beagleboard validation, I have no time for
merging all PM related functionality to the new kernel);
2) Setting voltage directly using VDDx_VSEL register in TPS65950;
3) Play with VFLOOR/VROOF registers in TPS65950 and toggling VMODE
input (which is grounded in BB-xM A3).
I implemented adjusting by changing VDD1_VSEL register value (VDDx =
VDDx_VSEL x 12.5mV + 0.6V, thus, for VDD1 = 1.35V VDD1_VSEL = 0x3C -
see "5.4.10.1.1 Direct Control" in SWCU050F, p.259).
It would be great if someone check this workaround by reviewing the
code. Thanks!
P.S. I made a couple of tests - the temperature of the chip is
slightly higher than with mpurate=800.