1.Can we just change the the ddr clock in uboot or the ddr driver which in the kernel ?
2.If we just change the ddr clock in uboot ,will the ddr driver which in the kernel change the the ddr clock?
3.How to change the ddr clock ?
4.And I have change the ddr clock in uboot,the as follows is the log ,is it right?
U-Boot 2009.08 ( 3鏈14 2014 - 05:56:35)
CPU: Freescale i.MX6 family TO1.1 at 792 MHz
Thermal sensor with ratio = 188
Temperature: 32 C, calibration data 0x5a500000
mx6q pll1: 792MHz
mx6q pll2: 528MHz
mx6q pll3: 480MHz
mx6q pll8: 50MHz
ipg clock : 27666666Hz
ipg per clock : 27666666Hz
uart clock : 80000000Hz
cspi clock : 60000000Hz
ahb clock : 55333333Hz
axi clock : 83000000Hz
emi_slow clock: 41500000Hz
ddr clock : 166000000Hz
usdhc1 clock : 83000000Hz
usdhc2 clock : 83000000Hz
usdhc3 clock : 83000000Hz
usdhc4 clock : 83000000Hz
nfc clock : 24000000Hz
Solved! Go to Solution.
Hi, cody
Our uboot's ddr clock is different from yours, see below, I wonder which uboot release you use, and did you do any changes? And to answer your question as below:
1. No, you can NOT change ddr clock directly in uboot, and there is no ddr driver in kernel, as ddr clock change need special flow, when uboot or kernel is running on ddr, its freq can NOT be changed. But we have busfreq driver which can change ddr clock automatically if there is no high speed devices active, you can check the busfreq DOC for detail.
2. No, you can NOT change ddr clock in uboot, we do NOT support that;
3. Please refer the busfreq driver and DOC;
4. Your uboot's ddr clock is wrong.
U-Boot 2009.08-00691-g117c045 (Jul 26 2013 - 09:02:56)
CPU: Freescale i.MX6 family TO1.1 at 792 MHz
Thermal sensor with ratio = 184
Temperature: 36 C, calibration data 0x58c50c69
mx6q pll1: 792MHz
mx6q pll2: 528MHz
mx6q pll3: 480MHz
mx6q pll8: 50MHz
ipg clock : 66000000Hz
ipg per clock : 66000000Hz
uart clock : 80000000Hz
cspi clock : 60000000Hz
ahb clock : 132000000Hz
axi clock : 198000000Hz
emi_slow clock: 99000000Hz
ddr clock : 396000000Hz
usdhc1 clock : 198000000Hz
usdhc2 clock : 198000000Hz
usdhc3 clock : 198000000Hz
usdhc4 clock : 198000000Hz
nfc clock : 24000000Hz
Hi, cody
Our uboot's ddr clock is different from yours, see below, I wonder which uboot release you use, and did you do any changes? And to answer your question as below:
1. No, you can NOT change ddr clock directly in uboot, and there is no ddr driver in kernel, as ddr clock change need special flow, when uboot or kernel is running on ddr, its freq can NOT be changed. But we have busfreq driver which can change ddr clock automatically if there is no high speed devices active, you can check the busfreq DOC for detail.
2. No, you can NOT change ddr clock in uboot, we do NOT support that;
3. Please refer the busfreq driver and DOC;
4. Your uboot's ddr clock is wrong.
U-Boot 2009.08-00691-g117c045 (Jul 26 2013 - 09:02:56)
CPU: Freescale i.MX6 family TO1.1 at 792 MHz
Thermal sensor with ratio = 184
Temperature: 36 C, calibration data 0x58c50c69
mx6q pll1: 792MHz
mx6q pll2: 528MHz
mx6q pll3: 480MHz
mx6q pll8: 50MHz
ipg clock : 66000000Hz
ipg per clock : 66000000Hz
uart clock : 80000000Hz
cspi clock : 60000000Hz
ahb clock : 132000000Hz
axi clock : 198000000Hz
emi_slow clock: 99000000Hz
ddr clock : 396000000Hz
usdhc1 clock : 198000000Hz
usdhc2 clock : 198000000Hz
usdhc3 clock : 198000000Hz
usdhc4 clock : 198000000Hz
nfc clock : 24000000Hz
Dear Yong:
Thank you very much for your kindly reply!
1.our original log "ddr clock 396000000Hz " is the same with yours.
after change the code in uboot from "
#define PLL2_PFD2_FREQ | 396000000" to
|
the ddr clock change to "ddr clock : 166000000Hz".
as you have said that "ou can NOT change ddr clock directly in uboot" ,
So the way to change the ddr clock is not the right way???
2. Can you tell me where to find the busfreq DOC ?
Thanks .
You can get our formal release package, there should be linux reference manual for it.
And you can NOT change any clock in uboot, actually, we do NOT support clk change in uboot, not just for ddr, but all clocks.