Hi Hans,
> On Oct 30, 2019, at 23:11, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>
> Hi,
>
> On 21-10-2019 09:17, Kai Heng Feng wrote:
>> 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?
>
> I just tried increasing the existing usleep between ON and RESET to:
>
> usleep_range(60000, 70000);
>
> And this does not help. Note that before we had quirks for devices with a SIS
> screen needed, where we avoided the reset on resume and instead did just an
> i2c_hid_set_power(client, I2C_HID_PWR_ON) for these.
>
> Which likely was to work around the same problem, these devices simply need a
> i2c_hid_set_power(client, I2C_HID_PWR_ON) after rest to function.
>
> Assuming other devices do come up in the "ON" state after reset then this
> will be a no-op for them and this should thus not impact their operation.
>
> Also I just noticed that 67b18dfb8cfc ("HID: i2c-hid: Remove runtime power management")
> has been added to 5.4-rc# as a fix, so we really need to get this in place
> to to not avoid regressing devices with a SIS touchscreen actually quite a
> few devices including some quite popular ones uses a SIS touchscreen, here
> is the list of devices I know about:
I agree we should use this workaround since increasing delay doesn't work.
Kai-Heng
>
> Asus T100HA
> Asus T200TA
> Peaq 10.1" C1010 2-in-1
> Toshiba Click Mini L9W-B
>
> Regards,
>
> Hans
>
>
>
>>> 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
