diff mbox series

[v2,2/2] HID: i2c-hid: goodix: Add support for "goodix,no-reset-during-suspend" property

Message ID 20230426093231.1466984-3-fshao@chromium.org
State New
Headers show
Series Fix Goodix touchscreen power leakage for MT8186 boards | expand

Commit Message

Fei Shao April 26, 2023, 9:32 a.m. UTC
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@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

---

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(+)

Comments

Fei Shao April 26, 2023, 2:24 p.m. UTC | #1
On Wed, Apr 26, 2023 at 10:05 PM Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Wed, Apr 26, 2023 at 2:33 AM Fei Shao <fshao@chromium.org> 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@chromium.org>
> > Reviewed-by: Douglas Anderson <dianders@chromium.org>
> >
> > ---
> >
> > 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".

Agree, I'll resend v3. Thanks for the feedback!

Regards,
Fei

>
> -Doug
diff mbox series

Patch

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);
@@ -91,6 +114,9 @@  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);