On Wed, Jul 26, 2023 at 02:52:48AM +0000, Jeffery Miller wrote: > There is a period of time between the psmouse deactivate and the > ability to communicate with the SMBus companion. Insert a > sleep after the deactivate to account for the delay and ensure > the SMBus companion is responsive. > > Attempting to read from the SMBus companion too quickly was causing > the touchpad on machines with an i801_smbus companion to stop working > after a sleep/resume cycle. > > On resume the rmi4_smbus would fail with errors reading the SMBus version > number: > ``` > [5454] i2c_i801:i801_check_post:414: i801_smbus 0000:00:1f.3: No response > smbus_result: i2c-0 a=02c f=0000 c=fd BYTE_DATA rd res=-6 > rmi4_smbus 0-002c: failed to get SMBus version number! > ... > rmi4_f01 rmi4-00.fn01: Failed to restore normal operation: -6. > rmi4_f01 rmi4-00.fn01: Resume failed with code -6. > rmi4_physical rmi4-00: Failed to suspend functions: -6 > rmi4_smbus 0-002c: Failed to resume device: -6 > ``` > In this case the rmi_smb_get_version fails with -ENXIO if it happens too > soon after the preceding serio_resume -> psmouse_deactivate call. > > On boot this issue could cause the touchpad to stay in the limited PS/2 > mode. This only reproduced in 1 in 10 boots on the Lenovo T440p. > Failures in the log on boot would show up as: > ``` > psmouse serio1: synaptics: Trying to set up SMBus access > [122] i2c_i801:i801_check_post:437: i801_smbus 0000:00:1f.3: No response > psmouse serio1: synaptics: SMbus companion is not ready yet > ``` > > Experimentation on the Lenovo T440p showed that a delay of 7-12ms on > resume allowed the companion to respond. > > The 30ms delay in this patch was chosen based on the linux-input message: > Link: https://lore.kernel.org/all/BYAPR03MB47572F2C65E52ED673238D41B2439@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > Signed-off-by: Jeffery Miller <jefferymiller@xxxxxxxxxx> Applied, thank you. -- Dmitry
