Hi,
On Wed, Apr 26, 2023 at 2:33 AM Fei Shao <fshao@xxxxxxxxxxxx> wrote:
>
> In the beginning, commit 18eeef46d359 ("HID: i2c-hid: goodix: Tie the
> reset line to true state of the regulator") introduced a change to tie
> the reset line of the Goodix touchscreen to the state of the regulator
> to fix a power leakage issue in suspend.
>
> After some time, the change was deemed unnecessary and was reverted in
> commit 557e05fa9fdd ("HID: i2c-hid: goodix: Stop tying the reset line to
> the regulator") due to difficulties in managing regulator notifiers for
> designs like Evoker, which provides a second power rail to touchscreen.
>
> However, the revert caused a power regression on another Chromebook
> device Steelix in the field, which has a dedicated always-on regulator
> for touchscreen and was covered by the workaround in the first commit.
>
> To address both cases, this patch adds the support for the new
> "goodix,no-reset-during-suspend" property in the driver:
> - When set to true, the driver does not assert the reset GPIO during
> power-down.
> Instead, the GPIO will be asserted during power-up to ensure the
> touchscreen always has a clean start and consistent behavior after
> resuming.
> This is for designs with a dedicated always-on regulator.
> - When set to false or unset, the driver uses the original control flow
> and asserts GPIO and disable regulators normally.
> This is for the two-regulator and shared-regulator designs.
>
> Signed-off-by: Fei Shao <fshao@xxxxxxxxxxxx>
> Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
>
> ---
>
> Changes in v2:
> - Do not change the regulator_enable logic during power-up.
>
> drivers/hid/i2c-hid/i2c-hid-of-goodix.c | 26 +++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid-of-goodix.c b/drivers/hid/i2c-hid/i2c-hid-of-goodix.c
> index 0060e3dcd775..fc4532fcadcc 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-of-goodix.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-of-goodix.c
> @@ -28,6 +28,7 @@ struct i2c_hid_of_goodix {
> struct regulator *vdd;
> struct regulator *vddio;
> struct gpio_desc *reset_gpio;
> + bool no_reset_during_suspend;
> const struct goodix_i2c_hid_timing_data *timings;
> };
>
> @@ -37,6 +38,20 @@ static int goodix_i2c_hid_power_up(struct i2chid_ops *ops)
> container_of(ops, struct i2c_hid_of_goodix, ops);
> int ret;
>
> + if (ihid_goodix->no_reset_during_suspend) {
> + /*
> + * This is not mandatory, but we assert reset here (instead of
> + * during power-down) to ensure the device will have a clean
> + * state after powering up, just like the normal scenarios will
> + * have.
> + *
> + * Note that in this case we assume the regulators should be
> + * (marked as) always-on, so the regulator core knows what to
> + * do with them in the following regulator_enable() calls
> + * despite regulator_disable() was not called previously.
> + */
> + gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
> + }
> ret = regulator_enable(ihid_goodix->vdd);
> if (ret)
> return ret;
> @@ -60,6 +75,14 @@ static void goodix_i2c_hid_power_down(struct i2chid_ops *ops)
> struct i2c_hid_of_goodix *ihid_goodix =
> container_of(ops, struct i2c_hid_of_goodix, ops);
>
> + /*
> + * Don't assert reset GPIO if it's set.
> + * Also, it's okay to skip the following regulator_disable() calls
> + * because the regulators should be always-on in this case.
> + */
> + if (ihid_goodix->no_reset_during_suspend)
> + return;
> +
> gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
> regulator_disable(ihid_goodix->vddio);
> regulator_disable(ihid_goodix->vdd);
I think the above is wrong. You should just skip the GPIO call when
"no_reset_during_suspend", not the regulator calls. As your code is
written, you'll enable the regulators over and over again in
"power_up" and never in "power_down".
-Doug
