Unable to boot into fastboot

I just got my Dragonboard 820c and it boots fine with its initial boot, but it’s on an older kernel than I would like. So I follow this tutorial and created a boot.img with kernel 5.4, but now I am on the regular fastboot instructions and I am stuck. My board won’t go into fastboot mode, when I hold (-) and start up my board it will just restart and never do as its supposed to.

I then go into terminal and type cat /dev/zero > /dev/disk/by-partlabel/boot but I get “Permissions Denied”, I tried to sudo it but get the same result. I tried to chmod /dev but the same result. I tried to superuser but I do not know the password and it is not linaro.

Once I get passed this step, I am also unsure what to do with my boot.img

Any advice would be helpful.

Try sudo su to switch to root before running the command.

which version of the Dragonboard 820c do you have, the one with UFS or eMMC?

sudo su seemed to do the trick.

I have updated my board to kernel 5.4, but the os seems to be running at half-speed. Everything is lagging and takes 5-6 seconds per click to open windows and boxes. Any idea? Is this just the norm?

The kernel source used for the snapshots doesn’t have the cpu frequency drivers, resulting in the CPU cores all running at fixed clocks, and unbelievably slow.

Take a peek here;

EDIT: I just checked my notes, and you would get the little cores running at 614 MHz, and the big cores running at a whopping 19 MHz.

Exact, linaro qcomlt 5.4 branch is not currently in good shape for 820c. I will check internally what we can do, possibly merge your branch or cherry pick the missing patches.