Hello, I tried running a spidev test program on linux 4.6 and I uncovered a problem with the sunxi clk framework.
Basically the system would lock up after running the test program. Digging deeper I found that it locks up with commit [47284e3e0f3c427c93f8583549b6c938e8a18015] spi: sun4i: allow transfers to set transmission speed This exposes a problem with the test program. I try to set the SPI sped to 1MHz but at other place the speed is multiplied by 1000 to save typing zeros so the actual requested speed is 1GHz. This commit probably allows that request to propagate leading to the observed system lockup. Given the parents OSC24M, pll6 and pll5 one of pll6 and pll5 is probably set up at 2GHz (or both in turn because due to some rounding neither goes fully up to 2GHz resulting in 864000000 SPI clock). Then the system locks up. I can limit the speed in the SPI driver which is rated at 100MHz in SoC manual (giving 200MHz pll) but the clk driver should probably limit the clock setting to sane speeds itself. I am not familiar with the sunxi-clk code and it has unfortunately no debug prints which would show what is programmed to what speed. Thanks Michal root@a10s:~/spidisp# ./spitest -r 50 -d -s 1000000 /dev/spidev2.0 Debug mode. spidev spi2.0: setup mode 0, 8 bits/w, 40000000 Hz max --> 0 spidev spi2.0: spi mode 0 spidev spi2.0: setup mode 0, 8 bits/w, 40000000 Hz max --> 0 spidev spi2.0: msb first spidev spi2.0: setup mode 0, 8 bits/w, 40000000 Hz max --> 0 spidev spi2.0: 0 bits per word spidev spi2.0: setup mode 0, 8 bits/w, 1000000000 Hz max --> 0 /dev/spidev2.0: spi mode 0x0, 8 bits per word, 1000000000 Hz maxspidev spi2.0: mclk spi2 (24000000) Sending 00 spidev spi2.0: mclk spi2 setting rate 2000000000Hz spidev spi2.0: mclk spi2 (864000000) spidev spi2.0: clkdiv 0 CDR2 0 regval 4096 spi_master spi2: spi2.0: timeout transferring 1 bytes@1000000000Hz for 100(100)ms spidev spi2.0: SPI transfer failed: -110 spi_master spi2: failed to transfer one message from queue xfer: Connection timed out buffer size: 1, result -110 buffer size: 1, result -110, Connection timed out Sending maximum buffer size: 0 Using gpio 50. Writing gpio export 50 to /sys/class/gpio/export. Reading gpio direction from /sys/class/gpio/gpio50/direction: in Reading gpio inversion from /sys/class/gpio/gpio50/active_low: 0 Writing gpio direction in to /sys/class/gpio/gpio50/direction. Reading gpio value from /sys/class/gpio/gpio50/value: 1 Writing gpio direction out to /sys/class/gpio/gpio50/direction. Writing gpio value 0 to /sys/class/gpio/gpio50/value. Writing gpio value 1 to /sys/class/gpio/gpio50/value. Writing gpio value 0 to /sys/class/gpio/gpio50/value. Writing gpio value 1 to /sys/class/gpio/gpio50/value. Sending 9f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 spidev spi2.0: mclk spi2 (864000000) spidev spi2.0: mclk spi2 setting rate 2000000000Hz spidev spi2.0: mclk spi2 (864000000) spidev spi2.0: clkdiv 0 CDR2 0 regval 4096
