Hi,
I am using the BBxM revC1, Ubuntu 12.04 with kernel 3.7.10-x10+.
Does anyone know if it is possible to run the BBxM at a different voltage than the one stated?
For example running at lowest frequency (300MHz) the system reports:
`
root@arm:/# cat /sys/class/regulator/regulator.4/name
vdd_mpu_iva
root@arm:/# cat /sys/class/regulator/regulator.4/microvolts
1012500
root@arm:/# cat /sys/class/regulator/regulator.4/max_microvolts
1450000
root@arm:/# cat /sys/class/regulator/regulator.4/min_microvolts
600000
`
Is it possible to change that “1012500” to lets say “1000000” or “900000”? I am testing for reliability so I want to push the voltage as low as possible.
According to the BBxM datasheet page 59 (7.7.5) VDD1 (vdd_mpu_iva) may be controlled using the SmartReflex controller (by I2C), configuring the output voltage of the TPS65950 between 0.6V and 1.45V in steps of 12.5mV (as stated before).
I know it may have to be done at Kernel cross-compiling stage, so digging into the kernel source code I found in /arch/arm/mach-omap2/omap3xxx_data.c
Line:58
`
/* 36xx */
/* VDD1 */
#define OMAP3630_VDD_MPU_OPP50_UV 1012500
#define OMAP3630_VDD_MPU_OPP100_UV 1200000
#define OMAP3630_VDD_MPU_OPP120_UV 1325000
#define OMAP3630_VDD_MPU_OPP1G_UV 1375000
struct omap_volt_data omap36xx_vddmpu_volt_data[] = {
VOLT_DATA_DEFINE(OMAP3630_VDD_MPU_OPP50_UV, OMAP3630_CONTROL_FUSE_OPP50_VDD1, 0xf4, 0x0c),
VOLT_DATA_DEFINE(OMAP3630_VDD_MPU_OPP100_UV, OMAP3630_CONTROL_FUSE_OPP100_VDD1, 0xf9, 0x16),
VOLT_DATA_DEFINE(OMAP3630_VDD_MPU_OPP120_UV, OMAP3630_CONTROL_FUSE_OPP120_VDD1, 0xfa, 0x23),
VOLT_DATA_DEFINE(OMAP3630_VDD_MPU_OPP1G_UV, OMAP3630_CONTROL_FUSE_OPP1G_VDD1, 0xfa, 0x27),
VOLT_DATA_DEFINE(0, 0, 0, 0),
};
`
which makes sense based on the report. Is modyfing the numbers of “#define OMAP3630_VDD_MPU_OPP50_UV 1012500” going to actually change the operating voltage at 300MHz?
Is there another place the parameters should be modified as well?
I know it may not be supported to tweak the kernel like this, but I am wondering at which level it is possible to modify these parameters.
Thanks in advance for any help,
Luis