The PCF8591 and PCA9685 drivers cannot be both loaded

[cristicsordas]

1. The address for the PCF8591 controller is 0x40. Using the instructions: "echo pca 0x40 > /sys/bus/i2c/devices/i2c-1/new_device" "/usr/bin/pca_load" (does a modprobe on the pca driver) the driver is loaded and works correctly.

The instruction "i2cdetect -y 1" shows this: 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: UU -- -- -- -- -- -- -- 48 -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: 70 -- -- -- -- -- -- --

The logs displayed with dmesg shows that the driver was loaded by the kernel:

• i2c i2c-1: new_device: Instantiated device pca at 0x40
• pca9685: pca_probe is entered on pca9685 From the application side the calls fopen, fwrite and ioctl works correctly. The python application sends through the socket communication messages to the driver. The motor actions are executed and the wheels are moving.

2. The address for the PCA9685 controller is 0x48. Using the instructions: echo pca 0x48 > /sys/bus/i2c/devices/i2c-1/new_device /usr/bin/pcf_load (does a modprobe on the pcf driver) the driver PCF8591 fails to be loaded correctly. The logs from dmesg show this messages:

   • i2c i2c-1: new_device: Instantiated device pcf at 0x48
   • pcf8591: pcf_probe is entered on pcf8591
   • pcf8591: create elem 16 (log message sent by the function create_list() )
   • pcf: probe of 1-0048 failed with error -16.

3. The following steps will make PCF8591 to work:

   • echo 0x48 > /sys/bus/i2c/devices/i2c-1/delete_device
   • echo 0x40 > /sys/bus/i2c/devices/i2c-1/delete_device
   • /usr/bin/pca_unload
   • /usr/bin/pcf_unload i2cdetect -y 1 displays this: 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: 40 -- -- -- -- -- -- -- 48 -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: 70 -- -- -- -- -- -- --
   • echo pcf 0x48 > /sys/bus/i2c/devices/i2c-1/new_device
   • /usr/bin/pcf_load i2cdetect -y 1 displays this: 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: 40 -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 70: 70 -- -- -- -- -- -- -- message from dmesg: i2c i2c-1: new_device: Instantiated device pcf at 0x48 pcf8591: pcf_probe is entered on pcf8591 pcf8591: create elem 16 At this moment the PCF8591 is working correctly. The sensor controlled by the PCF8591 sends expected values. Now I try loading the PCA9685:
   • echo pca 0x40 > /sys/bus/i2c/devices/i2c-1/new_device
   • /usr/bin/pca_load
   • i2cdetect -y 1 show no changes
   • this is the message from dmesg: "i2c i2c-1: new_device: Instantiated device pca at 0x40 pca9685: pca_probe is entered on pca9685 pca: probe of 1-0040 failed with error -16"
     Now pcf is working and pca not. Error -16 means that the driver is BUSY, but there is no driver loaded for that address.

The commit for the PCF8591 driver implementation is here: https://github.com/cristicsordas/raspi_robot/commit/02bb8846b8c3149c107f66bfd4882cf4726fda03#diff-b0ee59f04a5847d2756ac57c330b08528eec445c6fbb8f4634928bc96391a4c9

The commit for the PCA9685 implementation is here: https://github.com/cristicsordas/raspi_robot/commit/08700a4a0fc44f712919389077988b5f2b3dcf16

[dwalkes]

@cristicsordas I'd look into why misc_register can/does return EBUSY. Based on https://github.com/torvalds/linux/blob/4b810bf037e524b54669acbe4e0df54b15d87ea1/drivers/char/misc.c#L233 it looks like one way this would happen would be due to a minor number conflict. Can you prove this isn't happening?

[cristicsordas]

@dwalkes I changed the minor version of the pcf driver. Now they can both be loaded. Thank you

[cristicsordas]

fixed with the commit d7681b09dbf7f67b6ea0f54f48d215e4724b0bc9