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Subject[PATCH 0/2] HID: i2c-hid: add 60ms SET_POWER delay for Goodix touchpad
Date
I2C traffic after resumed from s2idle:

[ 275.312190] i2c_hid i2c-DELL096E:00: i2c_hid_set_power
[ 275.312191] i2c_hid i2c-DELL096E:00: __i2c_hid_command: cmd=05 00 01 08
[ 283.926905] i2c_hid i2c-DELL096E:00: i2c_hid_set_power
[ 283.926910] i2c_hid i2c-DELL096E:00: __i2c_hid_command: cmd=05 00 00 08
[ 283.927146] i2c_hid i2c-DELL096E:00: i2c_hid_set_or_send_report
[ 283.927149] i2c_hid i2c-DELL096E:00: __i2c_hid_command: cmd=05 00 37 03 06 00 05 00 07 00 00
[ 283.927872] i2c_hid i2c-DELL096E:00: i2c_hid_set_or_send_report
[ 283.927874] i2c_hid i2c-DELL096E:00: __i2c_hid_command: cmd=05 00 33 03 06 00 05 00 03 03 00
[ 283.929148] i2c_hid i2c-DELL096E:00: i2c_hid_set_or_send_report
[ 283.929151] i2c_hid i2c-DELL096E:00: __i2c_hid_command: cmd=05 00 35 03 06 00 05 00 05 03 00
# when touching touchpad:
[ 289.262675] i2c_hid i2c-DELL096E:00: input: 0b 00 01 00 00 00 00 00 00 00 00
[ 289.270314] i2c_hid i2c-DELL096E:00: input: 0b 00 01 00 fe 00 00 00 00 00 00
[ 289.276806] i2c_hid i2c-DELL096E:00: input: 0b 00 01 00 fd 00 00 00 00 00 00
[ 289.283863] i2c_hid i2c-DELL096E:00: input: 0b 00 01 00 fb 01 00 00 00 00 00
[ 289.291213] i2c_hid i2c-DELL096E:00: input: 0b 00 01 00 fa 02 00 00 00 00 00
[ 289.297932] i2c_hid i2c-DELL096E:00: input: 0b 00 01 00 f9 03 00 00 00 00 00
[ 289.304775] i2c_hid i2c-DELL096E:00: input: 0b 00 01 00 f9 03 00 00 00 00 00

On this device (Goodix touchpad 27C6:01F0), both Precision Touchpad
mode and a legacy Mouse mode are supported. When I2C SET_POWER ON is
issued, it would take as long as 60ms to complete state transition and
is then able to receive and execute further commands. On boot the
device is running under Mouse mode for legacy platform support, and
will be put to PTP mode with a SET_OR_SEND_REPORT command. If somehow
the time gap between the first SET_POWER ON and further
SET_OR_SEND_REPORT commands is less than 60ms, the device will still
operating under Mouse mode and gives reports like
"0b 00 01 00 fe 00 00 00 00 00 00".

On Linux system boot, it may take 500ms from i2c probe (SET_POWER ON)
to hid initialization (SET_OR_SEND_REPORT), so it will always be put
to PTP mode successfully. But when the device is put under s2idle
suspend and resumed, the hid reset resume process will be right after
i2c resume, so the device won't have enough time to complete its
state transition, which fails following SET_OR_SEND_REPORT executing
and therefore it operates under Mouse mode instead.

Currently Linux has a at most 5ms sleep in i2c_hid_hwreset(), but
according to HID over I2C Specification[1] section 7.2.8 "SET_POWER":

> The DEVICE must ensure that it transitions to the HOST
> specified Power State in under 1 second.

it can take as long as 1 second.

This changeset add a device property post-setpower-delay-ms and use it
to specify the delay after a SET_POWER command is issued for this
device.

References: https://bugzilla.kernel.org/show_bug.cgi?id=204991

You-Sheng Yang (2):
HID: i2c-hid: allow delay after SET_POWER
HID: i2c-hid: add 60ms SET_POWER delay for Goodix touchpad

.../bindings/input/hid-over-i2c.txt | 2 +
drivers/hid/i2c-hid/i2c-hid-core.c | 48 +++++++++++--------
include/linux/platform_data/i2c-hid.h | 3 ++
3 files changed, 33 insertions(+), 20 deletions(-)

--
2.23.0

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