• Doug Anderson's avatar
    i2c: rk3x: Restore clock settings at resume time · cbfff439
    Doug Anderson authored
    Depending on a number of factors including:
    - Which exact Rockchip SoC we're working with
    - How deep we suspend
    - Which i2c port we're on
    
    We might lose the state of the i2c registers at suspend time.
    Specifically we've found that on rk3399 the i2c ports that are not in
    the PMU power domain lose their state with the current suspend depth
    configured by ARM Tursted Firmware.
    
    Note that there are very few actual i2c registers that aren't configured
    per transfer anyway so all we actually need to re-configure are the
    clock config registers.  We'll just add a call to rk3x_i2c_adapt_div()
    at resume time and be done with it.
    
    NOTE: On rk3399 on ports whose power was lost, I put printouts in at
    resume time.  I saw things like:
      before: con=0x00010300, div=0x00060006
      after:  con=0x00010200, div=0x00180025
    Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
    Reviewed-by: default avatarDavid Wu <david.wu@rock-chips.com>
    Tested-by: default avatarDavid Wu <david.wu@rock-chips.com>
    [wsa: removed duplicate const]
    Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
    cbfff439
i2c-rk3x.c 35.2 KB