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  • Ben Gardner's avatar
    i2c: designware: must wait for enable · fba4adbb
    Ben Gardner authored
    One I2C bus on my Atom E3845 board has been broken since 4.9.
    It has two devices, both declared by ACPI and with built-in drivers.
    There are two back-to-back transactions originating from the kernel, one
    targeting each device. The first transaction works, the second one locks
    up the I2C controller. The controller never recovers.
    These kernel logs show up whenever an I2C transaction is attempted after
    this failure.
    i2c-designware-pci 0000:00:18.3: timeout in disabling adapter
    i2c-designware-pci 0000:00:18.3: timeout waiting for bus ready
    Waiting for the I2C controller status to indicate that it is enabled
    before programming it fixes the issue.
    I have tested this patch on 4.14 and 4.15.
    Fixes: commit 2702ea7d
     ("i2c: designware: wait for disable/enable only if necessary")
    Cc: linux-stable <> #4.13+
    Signed-off-by: default avatarBen Gardner <>
    Acked-by: default avatarJarkko Nikula <>
    Reviewed-by: default avatarJosé Roberto de Souza <>
    Signed-off-by: default avatarWolfram Sang <>