On Wed, 2018-08-29 at 19:42 +0200, Wolfram Sang wrote: > On Wed, Aug 29, 2018 at 02:20:19PM +0000, Joakim Tjernlund wrote: > > I see when I boot: > > [ 0.602608] i2c /dev entries driver > > [ 0.608010] mpc-i2c e0003000.i2c: timeout 1000000 us > > [ 0.623056] rtc-ds1307 1-0068: read: 17 33 13 04 29 08 18 > > [ 0.623096] rtc-ds1307 1-0068: read secs=17, mins=33, hours=13, mday=29, mon=7, year=118, wday=3 > > [ 0.623554] rtc-ds1307 1-0068: char device (253:0) > > [ 0.623609] rtc-ds1307 1-0068: registered as rtc0 > > [ 0.629544] i2c i2c-0: Added multiplexed i2c bus 1 > > [ 0.635788] i2c i2c-0: Added multiplexed i2c bus 2 > > [ 0.642584] i2c i2c-0: Added multiplexed i2c bus 3 > > [ 0.649617] i2c i2c-0: Added multiplexed i2c bus 4 > > [ 0.657617] i2c i2c-0: Added multiplexed i2c bus 5 > > [ 0.666545] i2c i2c-0: Added multiplexed i2c bus 6 > > [ 0.673730] i2c i2c-0: Added multiplexed i2c bus 7 > > [ 0.679968] i2c i2c-0: Added multiplexed i2c bus 8 > > [ 0.686263] i2c i2c-0: Added multiplexed i2c bus 9 > > [ 0.692515] i2c i2c-0: Added multiplexed i2c bus 10 > > [ 0.698832] i2c i2c-0: Added multiplexed i2c bus 11 > > [ 0.705256] i2c i2c-0: Added multiplexed i2c bus 12 > > [ 0.711551] i2c i2c-0: Added multiplexed i2c bus 13 > > [ 0.717979] i2c i2c-0: Added multiplexed i2c bus 14 > > [ 0.724342] i2c i2c-0: Added multiplexed i2c bus 15 > > [ 0.730654] i2c i2c-0: Added multiplexed i2c bus 16 > > [ 0.735635] i2c-mux-gpio e0000000.soc8321:i2cmux: 16 port mux on MPC adapter at 0xe0003000 adapter > > > > This looks like the I2C based RTC is accessed before i2c-mux-gpio is active? > > I once got confused by this, too. As part of the initialization of the > mux, all devices behind it are probed. During that probe, transactions > happen. Once all devices are probed, then the mux initialization is > finished, and *then* the "added bus" message is printed. > > Couldn't think of a better way back then, because we don't want to print > this message before everything with regard to the mux initialization was > successful. I don't get why you think mux init cannot be considered done until all devices are done too. This would make much more sense too me: [ 0.629544] i2c i2c-0: Added multiplexed i2c bus 1 [ 0.623056] rtc-ds1307 1-0068: read: 17 33 13 04 29 08 18 [ 0.623096] rtc-ds1307 1-0068: read secs=17, mins=33, hours=13, mday=29, mon=7, year=118, wday=3 [ 0.623554] rtc-ds1307 1-0068: char device (253:0) [ 0.623609] rtc-ds1307 1-0068: registered as rtc0 [ 0.635788] i2c i2c-0: Added multiplexed i2c bus 2 .... Good to know this is just a "mirage" though, thanks. > > At least, this is how I recall all of this.
