Ok. Found it. Our application is started via SYSTEMCTL at boot time. In its starting script, I found (simplified view): | dtoverlay i2c-gpio i2c_gpio_sda=0 i2c_gpio_scl=1| | echo "24c32 0x50" > /sys/class/i2c-adapter/xxx/new_device| | hexdump -C /sys/class/i2c-adapter/i2c-3/3-0050/eeprom | |On 5.4.42, after the call to DTOVERLAY, the path "xxx" changes from "i2c-3" to "i2c-11" ...| |Then, the ECHO fails, the HEXDUMP too and so on. | | | |2 years back, we took this part of code from EEPFLASH.SH (||https://github.com/raspberrypi/hats/tree/master/eepromutils)| |This tool was updated 10 months back, to avoid conflicts on RPI4 (||https://github.com/raspberrypi/hats/commit/42c532fcb2febf4fe57bde6511c31fc0d4515627), and now, it's written like| | dtoverlay i2c-gpio i2c_gpio_sda=0 i2c_gpio_scl=1 bus=10| | | |This gave my an idea. If I force "bus=3", all works as expected, and I'm able to read the EEPROM. | |So, ... On 5.4.42, I would say that some i2c-related kernel module has changed its behavior, when "bus" parameter is not set, to avoid some conflict on RPI4 ...| | | || | | |Stephan. | | | || ||On 16-Jun-20 01:07, Stephan GUILLOUX wrote: > Some progress. > > I reinstalled a SD and updated manually all the kernel RPMS that I can > find. > > Only last kernel has this change (5.4.28 is still ok). > > > > On 15-Jun-20 22:59, Stephan GUILLOUX wrote: > >> Hello all, >> >> >> Maybe some will be able to help a bit. >> >> I'm running 2 Raspberries 3B+, with the same old CentOS image, >> freshly prepared. >> >> Both run raspberrypi2-kernel 4.19.xx >> >> Both Raspberry have a hat, with a valid EEPROM. >> >> >> On both, the application I'm in charge of, has R/W access to >> >> /sys/class/i2c-adapter/i2c-3/3-0050/eeprom >> >> >> On one Raspberry, I update the kernel and only the kernel (yum update >> raspberrypi2-kernel) and I come to 5.4.42. >> >> After reboot, the whole content of /sys/class has changed, regarding >> I2C. >> >> 4.19.94: >> >> [root at Raspberry-DD7BD7 OLD ~]$ ls -al /sys/bus/i2c/devices/ >> total 0 >> drwxr-xr-x. 2 root root 0 Jan 1 1970 . >> drwxr-xr-x. 4 root root 0 Jan 1 1970 .. >> lrwxrwxrwx. 1 root root 0 Jan 1 1970 3-0050 -> >> ../../../devices/platform/ffffffff.i2c/i2c-3/3-0050 >> lrwxrwxrwx. 1 root root 0 Jan 1 1970 i2c-3 -> >> ../../../devices/platform/ffffffff.i2c/i2c-3 >> [root at Raspberry-DD7BD7 OLD ~]$ ls -al /sys/bus/i2c/devices/3-0050/eeprom >> >> 5.4.42: >> >> [root at CertifBox-8AC500 OLD ~]$ ls -al /sys/class/i2c-adapter/ >> total 0 >> drwxr-xr-x. 2 root root 0 Jan 1 1970 . >> drwxr-xr-x. 54 root root 0 Jan 1 1970 .. >> lrwxrwxrwx. 1 root root 0 Jun 15 22:53 i2c-11 -> >> ../../devices/platform/ffffffff.i2c/i2c-11 >> [root at CertifBox-8AC500 OLD ~]$ >> >> >> Any idea where I can find this EEPROM file ? >> >> A module option, maybe ? >> >> >> Regards, >> >> Stephan. >> >> >> >> >> _______________________________________________ >> Arm-dev mailing list >> Arm-dev at centos.org >> https://lists.centos.org/mailman/listinfo/arm-dev > _______________________________________________ > Arm-dev mailing list > Arm-dev at centos.org > https://lists.centos.org/mailman/listinfo/arm-dev