• Douglas Anderson's avatar
    Input: elants_i2c - properly handle the reset GPIO when power is off · a85fbd64
    Douglas Anderson authored
    As can be seen in elants_i2c_power_off(), we want the reset GPIO
    asserted when power is off. The reset GPIO is active low so we need
    the reset line logic low when power is off to avoid leakage.
    
    We have a problem, though, at probe time. At probe time we haven't
    powered the regulators on yet but we have:
    
      devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW);
    
    While that _looks_ right, it turns out that it's not. The
    GPIOD_OUT_LOW doesn't mean to init the GPIO to low. It means init the
    GPIO to "not asserted". Since this is an active low GPIO that inits it
    to be high.
    
    Let's fix this to properly init the GPIO. Now after both probe and
    power off the state of the GPIO is consistent (it's "asserted" or
    level low).
    
    Once we fix this, we can see that at power on time we no longer to
    assert the reset GPIO as the first thing. The reset GPIO is _always_
    asserted before powering on. Let's fix powering on to account for
    this.
    
    Fixes: afe10358 ("Input: elants_i2c - wire up regulator support")
    Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
    Link: https://lore.kernel.org/r/20221117123805.1.I9959ac561dd6e1e8e1ce7085e4de6167b27c574f@changeidSigned-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
    a85fbd64
elants_i2c.c 41.5 KB