Hi Fei,
On Wed, Apr 26, 2023 at 10:44:22PM +0800, Fei Shao 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 disables 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>
Great work; one tiny nit below. If you do not agree with it or have found
precedent that suggests it is OK, feel free to ignore it. Either way:
Reviewed-by: Jeff LaBundy <jeff@xxxxxxxxxxx>
>
> ---
>
> Changes in v3:
> - In power-down, only skip the GPIO but not the regulator calls if the
> flag is set
>
> Changes in v2:
> - Do not change the regulator_enable logic during power-up.
>
> drivers/hid/i2c-hid/i2c-hid-of-goodix.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid-of-goodix.c b/drivers/hid/i2c-hid/i2c-hid-of-goodix.c
> index 0060e3dcd775..3ed365b50432 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 +38,14 @@ 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) {
> + /*
> + * We assert reset GPIO 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.
> + */
> + gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
> + }
I don't think curly braces are technically required here, as there is only
one statement within the conditional despite the comments making it appear
otherwise. Maybe this would work too:
/* ... */
if (...)
gpiod_set_value_cansleep(...);
Again however, I do not feel strongly about this.
> ret = regulator_enable(ihid_goodix->vdd);
> if (ret)
> return ret;
> @@ -60,7 +69,9 @@ 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);
>
> - gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
> + if (!ihid_goodix->no_reset_during_suspend)
> + gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
> +
> regulator_disable(ihid_goodix->vddio);
> regulator_disable(ihid_goodix->vdd);
> }
> @@ -91,6 +102,9 @@ static int i2c_hid_of_goodix_probe(struct i2c_client *client)
> if (IS_ERR(ihid_goodix->vddio))
> return PTR_ERR(ihid_goodix->vddio);
>
> + ihid_goodix->no_reset_during_suspend =
> + of_property_read_bool(client->dev.of_node, "goodix,no-reset-during-suspend");
> +
> ihid_goodix->timings = device_get_match_data(&client->dev);
>
> return i2c_hid_core_probe(client, &ihid_goodix->ops, 0x0001, 0);
> --
> 2.40.1.495.gc816e09b53d-goog
>
Kind regards,
Jeff LaBundy
