I am not sure the LCD Clock is related to Calibrating or not.
Since PXA270, we should change LCD Clock when cpu clock changed.
The following config is used in mb-applet-powerctrl. They are very stable stable in C1000, C3XXX.
[PXA270]
# do not change below
PathCCCR=/proc/zaurus/CCCR
PathVCORE=/proc/zaurus/VCORE
MaxFreq=5
DefaultFreq=3
#cpu clock, CCCR, VCORE
freq0=104,2000204,4,1
freq1=208,2000206,6,1
freq2=312,2000208,8,1
freq3=416,2000210,a,1
#2000210: CPU clock 416MHz system bus 208MHz LCD104MHz(default)
freq4=520,2000214,c,1
#freq4=520,2000290,c,1
#a000214: CPU clock 520MHz system bus 260MHz LCD130MHz
#2000290: CPU clock 520MHz system bus 208MHz LCD104MHz
#2000214: CPU clock 520MHz system bus 260MHz LCD 64MHz
freq5=624,2000218,e,1
#freq5=624,2000310,e,1
#a000218: CPU clock 624MHz system bus 312MHz LCD156MHz
#2000310: CPU clock 624MHz system bus 208MHz LCD104MHz
#2000218: CPU clock 624MHz system bus 312MHz LCD 78MHz