It has been clearly described in the last post. This cannot be burned by yourself. It is burned during production testing. I attach it again.
It says "Burned by tester program, forindicating IC core speed (Hotburn may not be used)."
Industrial part and Consumer part have different life times. This is in i.MX 6ULL Product Usage Lifetime Estimates (AN5337).
If you force a higher frequency in the software than its grade defined, the life time will inevitably be shortened.
According to your idea, everyone should buy a cheaper Consumer part and burn it into an industrial part by themselves.
It will save lots of money including my running projects.
According to your idea, another case is just burn fuse of industrial part, it can run at 900M without life time impact.
Why NXP does not have 900M industrial part?
Why are there still different parts of different grades for sale?
Remove the other frequencies? Have you ever tried it? Just looking at the code, it doesn't work.
You can only modify the following code, but I think it is only for testing purpose.
As I said before, If you force a higher frequency in the software, the life time will inevitably be shortened.
if (of_machine_is_compatible("fsl,imx6ull")) {
#if 0
if (val < OCOTP_CFG3_6ULL_SPEED_792MHZ)
imx6x_disable_freq_in_opp(dev, 792000000);
if (val != OCOTP_CFG3_6ULL_SPEED_900MHZ)
imx6x_disable_freq_in_opp(dev, 900000000);
#endif
}
All frequencies are already in the device tree. The code will determine the chip type based on different fuses and then modify the DTB in real-time.
https://github.com/nxp-imx/linux-imx/blob/lf-6.6.3-1.0.0/drivers/cpufreq/imx6q-cpufreq.c
#define OCOTP_CFG3_6UL_SPEED_696MHZ 0x2
#define OCOTP_CFG3_6ULL_SPEED_792MHZ 0x2
#define OCOTP_CFG3_6ULL_SPEED_900MHZ 0x3
static int imx6ul_opp_check_speed_grading(struct device *dev)
{
u32 val;
int ret = 0;
if (of_property_present(dev->of_node, "nvmem-cells")) {
ret = nvmem_cell_read_u32(dev, "speed_grade", &val);
if (ret)
return ret;
} else {
struct device_node *np;
void __iomem *base;
np = of_find_compatible_node(NULL, NULL, "fsl,imx6ul-ocotp");
if (!np)
np = of_find_compatible_node(NULL, NULL,
"fsl,imx6ull-ocotp");
if (!np)
return -ENOENT;
base = of_iomap(np, 0);
of_node_put(np);
if (!base) {
dev_err(dev, "failed to map ocotp\n");
return -EFAULT;
}
val = readl_relaxed(base + OCOTP_CFG3);
iounmap(base);
}
/*
* Speed GRADING[1:0] defines the max speed of ARM:
* 2b'00: Reserved;
* 2b'01: 528000000Hz;
* 2b'10: 696000000Hz on i.MX6UL, 792000000Hz on i.MX6ULL;
* 2b'11: 900000000Hz on i.MX6ULL only;
* We need to set the max speed of ARM according to fuse map.
*/
val >>= OCOTP_CFG3_SPEED_SHIFT;
val &= 0x3;
if (of_machine_is_compatible("fsl,imx6ul"))
if (val != OCOTP_CFG3_6UL_SPEED_696MHZ)
imx6x_disable_freq_in_opp(dev, 696000000);
if (of_machine_is_compatible("fsl,imx6ull")) {
if (val < OCOTP_CFG3_6ULL_SPEED_792MHZ)
imx6x_disable_freq_in_opp(dev, 792000000);
if (val != OCOTP_CFG3_6ULL_SPEED_900MHZ)
imx6x_disable_freq_in_opp(dev, 900000000);
}
return ret;
}
Hi,
My idea was to remove the other frequencies before blowing the highlighted fuse. You could try to only add the 792MHz node in DTS, if not, you should modify the fuses if your part number matches the 08 code.
Regards,
It has been clearly described in the last post. This cannot be burned by yourself. It is burned during production testing. I attach it again.
It says "Burned by tester program, forindicating IC core speed (Hotburn may not be used)."
Industrial part and Consumer part have different life times. This is in i.MX 6ULL Product Usage Lifetime Estimates (AN5337).
If you force a higher frequency in the software than its grade defined, the life time will inevitably be shortened.
According to your idea, everyone should buy a cheaper Consumer part and burn it into an industrial part by themselves.
It will save lots of money including my running projects.
According to your idea, another case is just burn fuse of industrial part, it can run at 900M without life time impact.
Why NXP does not have 900M industrial part?
Why are there still different parts of different grades for sale?
Remove the other frequencies? Have you ever tried it? Just looking at the code, it doesn't work.
You can only modify the following code, but I think it is only for testing purpose.
As I said before, If you force a higher frequency in the software, the life time will inevitably be shortened.
if (of_machine_is_compatible("fsl,imx6ull")) {
#if 0
if (val < OCOTP_CFG3_6ULL_SPEED_792MHZ)
imx6x_disable_freq_in_opp(dev, 792000000);
if (val != OCOTP_CFG3_6ULL_SPEED_900MHZ)
imx6x_disable_freq_in_opp(dev, 900000000);
#endif
}
