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On 2019-09-25T04:51:35+00:00 vicamo wrote:

Created attachment 285163
dmesg, v5.3.1, i2c-hid.debug=1 hid.debug=1

I2C traffic after resume:

[ 275.148083] i2c_hid i2c-CUST0000:00: i2c_hid_set_power
[ 275.148084] i2c_hid i2c-CUST0000:00: __i2c_hid_command: cmd=05 00 01 08
[ 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
[ 284.077891] i2c_hid i2c-CUST0000:00: i2c_hid_set_power
[ 284.077892] i2c_hid i2c-CUST0000:00: __i2c_hid_command: cmd=05 00 00 08

# 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, 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 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.

Reply at:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1842532/comments/3

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On 2019-09-25T04:55:43+00:00 vicamo wrote:

http://download.microsoft.com/download/7/d/d/7dd44bb7-2a7a-4505-ac1c-
7227d3d96d5b/hid-over-i2c-protocol-spec-v1-0.docx

Reply at:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1842532/comments/4


** Changed in: linux
       Status: Unknown => Confirmed

** Changed in: linux
   Importance: Unknown => Medium

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Title:
  Touchpad stops working after resuming from s2idle

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