Hi Hans,
> On Oct 21, 2019, at 5:47 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>
> Before commit 67b18dfb8cfc ("HID: i2c-hid: Remove runtime power
> management"), any i2c-hid touchscreens would typically be runtime-suspended
> between the driver loading and Xorg or a Wayland compositor opening it,
> causing it to be resumed again. This means that before this change,
> we would call i2c_hid_set_power(OFF), i2c_hid_set_power(ON) before the
> graphical session would start listening to the touchscreen.
>
> It turns out that at least some SIS touchscreens, such as the one found
> on the Asus T100HA, need a power-on command after reset, otherwise they
> will not send any events.
As You-Sheng pointed out before, device may need a 60ms delay between ON and RESET command.
Does adding the delay help?
Kai-Heng
>
> Fixes: 67b18dfb8cfc ("HID: i2c-hid: Remove runtime power management")
> Cc: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/hid/i2c-hid/i2c-hid-core.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
> index d9c55e30f986..04c088131e04 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-core.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
> @@ -447,8 +447,12 @@ static int i2c_hid_hwreset(struct i2c_client *client)
> if (ret) {
> dev_err(&client->dev, "failed to reset device.\n");
> i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
> + goto out_unlock;
> }
>
> + /* At least some SIS devices need this after reset */
> + ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
> +
> out_unlock:
> mutex_unlock(&ihid->reset_lock);
> return ret;
> --
> 2.23.0
>
