Hi,
On 31-10-2019 07:23, Kai-Heng Feng wrote:
Hi Hans,
On Oct 31, 2019, at 01:39, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
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.
I just checked the spec again, seems like ON before RESET in probe is unnecessary.
Does removing the ON command in probe help?
I just tried, removing the ON command done before the RESET does not help.
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
