Try lsi2c on your system and see if the "PATHs" are unique. on github: https://github.com/costad2/i2cdev This should provide you with a unique and unchanging path for all of you i2c devices. Then when the conflicting/inconsistent bus appears its path will not change even if its i2c-%d changes. - Danielle On Wed, Mar 11, 2015 at 9:11 PM, Bob Feretich <bob.feretich@xxxxxxxxxxxxxxx> wrote: > I am working on a BeagleBone Black (BBB) Cape that contains a PCA9548 multiplexer (mux). The BBB uses two I2C buses, i2c-0 for power management and i2c-2 for Cape discovery and other general use. I have created a dtsi file to describe the mux on my Cape per the Linux Documentation instructions. > > > ... > > &i2c2 { > i2cmux@77 { > compatible = "nxp,pca9548"; > #address-cells = <1>; > #size-cells = <0>; > reg = <0x77>; > }; > ... > > When I boot Linux (3.14 kernel) without the cape attached I see i2c-0 and i2c-2... > ubuntu@arm:~$ ls /dev/i2* > /dev/i2c-0 /dev/i2c-2 > ubuntu@arm:~$ i2cdetect -l > i2c-0 i2c OMAP I2C adapter I2C adapter > i2c-2 i2c OMAP I2C adapter I2C adapter > > But, I can also see in dmesg that i2c-0 probing is deferred until after i2c-2. > [ 2.186756] omap_i2c 44e0b000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c0_pins, deferring probe > [ 2.186803] platform 44e0b000.i2c: Driver omap_i2c requests probe deferral > [ 2.193949] omap_i2c 4819c000.i2c: bus 2 rev0.11 at 100 kHz > ...snipped... > [ 2.965899] tps65217 0-0024: TPS65217 ID 0xe version 1.2 > [ 2.967376] at24 0-0050: 32768 byte 24c256 EEPROM, writable, 1 bytes/write > [ 2.967500] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 400 kHz > > > This causes a problem when I boot with the Cape attached. > 1) Probing is deferred on i2c-0. > 2) i2c-2 is probed, the mux is discovered, and the child buses are > > assigned i2c-0, i2c-1, and i2c-3 through i2c-8. > 3) The original i2c-0 bus is then probed, but since it requires the name i2c-0 and that name is already used, adapter addition fails. > > ubuntu@arm:~$ ls /dev/i2* > /dev/i2c-0 /dev/i2c-2 /dev/i2c-4 /dev/i2c-6 /dev/i2c-8 > /dev/i2c-1 /dev/i2c-3 /dev/i2c-5 /dev/i2c-7 > ubuntu@arm:~$ i2cdetect -l > i2c-0 i2c i2c-2-mux (chan_id 0) I2C adapter > i2c-1 i2c i2c-2-mux (chan_id 1) I2C adapter > i2c-2 i2c OMAP I2C adapter I2C adapter > i2c-3 i2c i2c-2-mux (chan_id 2) I2C adapter > i2c-4 i2c i2c-2-mux (chan_id 3) I2C adapter > i2c-5 i2c i2c-2-mux (chan_id 4) I2C adapter > i2c-6 i2c i2c-2-mux (chan_id 5) I2C adapter > i2c-7 i2c i2c-2-mux (chan_id 6) I2C adapter > i2c-8 i2c i2c-2-mux (chan_id 7) I2C adapter > > > From dmesg... > [ 2.186754] omap_i2c 44e0b000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c0_pins, deferring probe > [ 2.186802] platform 44e0b000.i2c: Driver omap_i2c requests probe deferral > [ 2.193953] omap_i2c 4819c000.i2c: bus 2 rev0.11 at 100 kHz > ...snipped... > [ 2.753254] i2c /dev entries driver > [ 2.756232] i2c i2c-2: Added multiplexed i2c bus 0 > [ 2.756992] i2c i2c-2: Added multiplexed i2c bus 1 > [ 2.757690] i2c i2c-2: Added multiplexed i2c bus 3 > [ 2.758361] i2c i2c-2: Added multiplexed i2c bus 4 > [ 2.759065] i2c i2c-2: Added multiplexed i2c bus 5 > [ 2.759717] i2c i2c-2: Added multiplexed i2c bus 6 > [ 2.760392] i2c i2c-2: Added multiplexed i2c bus 7 > [ 2.761065] i2c i2c-2: Added multiplexed i2c bus 8 > [ 2.761081] pca954x 2-0077: registered 8 multiplexed busses for I2C switch > > ...snipped... > [ 2.951717] omap_i2c 44e0b000.i2c: failure adding adapter > ...snipped... > [ 2.964249] omap_i2c: probe of 44e0b000.i2c failed with error -16 > ... snipped ... > [ 8.997764] cpu cpu0: of_pm_voltdm_notifier_register: Failed to get cpu0 regulator/voltdm: -517 > [ 8.997796] cpu cpu0: cpu0 clock notifier not ready, retry > [ 9.082435] platform cpufreq-cpu0.0: Driver cpufreq-cpu0 requests probe deferral > [ 9.194548] slave hdmi.38: could not get i2c > > > Is there a quick work-around for this problem (prevent deferred probing or defer both bus probes)? > > Is there a way that I can force the child buses to use names that don't conflict with BBB predefined buses (perhaps a property or alias in the device tree)? > > Will the future "multiple i2c multiplexers on the same bus" solution fix this problem? > > Any other ideas for a work around? > > Regards, > > Bob Feretich > -- > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- - Danielle Costantino -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
