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Silvan's avatar
Silvan
Icon for Occasional Contributor rankOccasional Contributor
6 years ago
Solved

driver for HPS I2C Hardware in u-boot 04.2020 deactivates clocks

Hello all, I have an Arria 10 SoC device on our custom board. The board boots from an SD Card, loading u-boot and than a Linux kernel. Until now, I used an old u-boot build flow utilized Quartus an...
  • MWill5's avatar
    MWill5
    5 years ago

    Hello,

    We had a similar problem trying to migrate to the socfpga_v2021.04 branch of uBoot. We have an on-board EEPROM (I2C) that contains factory configuration data that is needed during the uBoot TPL phase.

    We are seeing that the designware_i2c I2C controller is resetting the l4_sp_clk when it is removed prior to starting the linux kernel. The result is that there is a bus hang when the kernel tries to access the UART peripheral (which needs that clock). The kernel we are trying to use is from 4.9.78-ltsi. It's possible that later versions of the kernel properly re-enable the l4_sp_clk, but this doesn't seem to be the case for our particular configuration (which works fine with uboot 2014.10). We also had to set the socfpga_legacy_reset_compat=1 uBoot environment variable as well, as without it this version of uBoot will reset all the peripherals as it switches to linux, resulting in a similar hang.

    Our work-around can be found in this patch here:

    Critical Link LLC git repositories. - u-boot-socfpga.git/blobdiff - drivers/i2c/designware_i2c.c

    -Mike

MWill5's avatar
MWill5
Icon for New Contributor rankNew Contributor
5 years ago

Hello,

We had a similar problem trying to migrate to the socfpga_v2021.04 branch of uBoot. We have an on-board EEPROM (I2C) that contains factory configuration data that is needed during the uBoot TPL phase.

We are seeing that the designware_i2c I2C controller is resetting the l4_sp_clk when it is removed prior to starting the linux kernel. The result is that there is a bus hang when the kernel tries to access the UART peripheral (which needs that clock). The kernel we are trying to use is from 4.9.78-ltsi. It's possible that later versions of the kernel properly re-enable the l4_sp_clk, but this doesn't seem to be the case for our particular configuration (which works fine with uboot 2014.10). We also had to set the socfpga_legacy_reset_compat=1 uBoot environment variable as well, as without it this version of uBoot will reset all the peripherals as it switches to linux, resulting in a similar hang.

Our work-around can be found in this patch here:

Critical Link LLC git repositories. - u-boot-socfpga.git/blobdiff - drivers/i2c/designware_i2c.c

-Mike

  • Silvan's avatar
    Silvan
    Icon for Occasional Contributor rankOccasional Contributor
    5 years ago

    Hi Mike,

    Thanks for that nice patch. The system works with it. Also, many thanks for the hint to the u-boot variable socfpga_legacy_reset_compat

    Silvan