Hi Sergey, [add Noralf and drop the Broadcom guys from CC since this specific to the RPi] Am 07.12.18 um 14:36 schrieb Sergey Suloev: > Greetings, > > I am dealing with a custom hardware based on RPI3B running kernel 4.19 > (or 4.20). > My device has 2 slaves on I2C bus: codec WM8731 (on address 0x1a) and > clock generator si5351a (on 0x60). > > It has been a lot of time for me fighting with an I2C issue which does > not allow the two I2C devices work correctly together: I2C bus hangs > up at kernel boot. Could you give some kernel message or some measurements of the I2C line states? > The issue happens in 50-70% boot cases and the fail percentage > noticeably depends on the bus clock set in DTS: the more frequency > set the less fail percentage. I assume you don't use the downstream cpufreq driver, which could generate interferences on the clock. > The kernel itself loads successfully, I can ssh to the RPI in order to > issue "i2cdetect -y 0" and make sure that I2C bus is locked completely > and not responding. > AFAIK this I2C0 is shared with the VideoCore. Did you already tried I2C1 which should be exclusive for the ARM core(s)? Stefan > So far I have found the only way to make it work : to compile si5351a > driver into kernel and use wm8731 driver as a module. > This probably makes the clock driver load 100% before the codec and > I2C bus does not hang up. > Since it can be fixed this way the problem really looks like a "race > condition" in I2C bus/driver. > > Would be really nice to know your opinion and possible ways to fix this. > > > Best regards, > > Sergey >
