I spent the last couple days pulling my hair out trying to figure out why flashrom kept failing to flash my Lenovo x220 with coreboot. I was able to get a successful backup of my firmware after shortening the cables, but for some reason writing and image kept failing. When running the command the chip would randomly not be found or sometimes acted like it disconnected during the operation. At this point my laptop was bricked and I was having trouble finding anyone else on the internet having the same problem.
I am using the BeagleBone Black as a SPI flasher and it has been successful in the past with my Lenovo x200s. The flash chip was powered with 3.3V from a cheap breadboard power supply. The Libreboot project provides a really nice guide and some troubleshooting tips.
I was suspicious that the power supply wasn’t supplying a stable 3.3V so I ordered an expensive Sparkfun model and a Teensy 3.2 as a good backup plan.
After receiving my order, the off brand and Sparkfun breadboard power supplies did show any positive improvements to my problem. However, pulling 3.3 voltage from the Teensy did. I was able to flash and boot my laptop. I believe my main issue was the fact that voltage was not stable or high enough to properly flash the chip. The chart below shows the measured voltage outputs using a decent multimeter:
|5V – 2A||9V – 650mA||12V – 1A (Linksys)||USB|
This chart makes me think that my original method using the black breadboard power supply and the Linksys wall adapter should have worked. However, I am not sure how to measure voltage under draw and maybe it dropped to low when the write started. I also did not test all of the above options for flashing. It is important to note how much the power supplies are affected by different power adapters.
My theory is that I did not have problems flashing my x200s because the flash chip was older and smaller which required less voltage to write. Reading a chip might also require less voltage which is how I got a good backup and was able to build my coreboot image. I do not pretend to be an expert in electronics so please correct me in the comments if you have a better idea than me. I am just trying to provide my findings to hopefully help another person.
Next time my flash is failing the first thing I will do is pull out a multimeter and double check the voltage.