spidev1.x -vs- spidev2.x ?

Anyone know what determines which number will be used for spidev when
the BB-SPI1 cape is loaded?

I'm using Debian 8.5 (2016-08-14) image.

BB-SPI1 cape will create /dev/spidev1.x when running 4.1.14-bone17 kernel


BB-SPI1 cape will create /dev/spidev2.x when running 4.1.15-bone18 kernel

My reason for asking is that I can *not* get fbtft working for TFT LCD
on SPI1 when using 4.1.15-bone18. However, fbtft works OK on the
earlier 4.1.14-bone17 kernel.

Details in this gist:


Try loading spidev via /boot/uEnv.txt, as your dealing with the spi DMA fix first introduced in bone18

It was later tweaked again in that time frame.