On Thursday 01 February 2018 21:23:40 Mario.Limonciello@dell.com wrote:
> > -----Original Message-----
> > From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com]
> > Sent: Thursday, February 1, 2018 3:14 PM
> > To: Limonciello, Mario <Mario_Limonciello@Dell.com>
> > Cc: Pali Rohár <pali.rohar@gmail.com>; linux-input@vger.kernel.org; lkml <linux-
> > kernel@vger.kernel.org>
> > Subject: Re: Dell docking station & Dell Embedded Controller & PS/2 devices
> > 
> > On Thu, Feb 1, 2018 at 11:35 AM,  <Mario.Limonciello@dell.com> wrote:
> > >
> > >
> > >> -----Original Message-----
> > >> From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com]
> > >> Sent: Thursday, February 1, 2018 1:30 PM
> > >> To: Pali Rohár <pali.rohar@gmail.com>
> > >> Cc: Limonciello, Mario <Mario_Limonciello@Dell.com>; linux-
> > >> input@vger.kernel.org; linux-kernel@vger.kernel.org
> > >> Subject: Re: Dell docking station & Dell Embedded Controller & PS/2 devices
> > >>
> > >> Hi Pali,
> > >>
> > >> On Wed, Jan 24, 2018 at 11:41:21AM +0100, Pali Rohár wrote:
> > >> > Hi Dmitry!
> > >> >
> > >> > I'm observing a problem with internal touchpad (handled by psmouse.ko)
> > >> > on Dell laptops connected to Dell E docking station. When I connect
> > >> > external PS/2 keyboard to docking station then internal laptop touchpad
> > >> > switch from multitouch absolute mode to relative bare PS/2 mode.
> > >> >
> > >> > And because ALPS driver in psmouse.ko is capable to process interleaved
> > >> > bare 3-byte PS/2 packets with 6-byte ALPS packets (which handles
> > >> > trackstick data on some ALPS models), ALPS driver does not show any
> > >> > message about this "downgrade" from multitouch to bare mode. And
> > >> > continue working in bare mode.
> > >> >
> > >> > When I rmmod psmouse and modprobe it again, then touchpad switch back to
> > >> > multitouch mode.
> > >> >
> > >> > Mario told me that Dell Embedded Controller, which handle internal
> > >> > keyboard, internal touchpad and external PS/2 keyboard, automatically
> > >> > send RESET command to *all* those devices when external PS/2 keyboard is
> > >> > connected. Therefore this is reason why touchpad downgrade to to bare
> > >> > mode. And according to Mario, host system should issue vendor specific
> > >> > PS/2 commands to re-initialize all PS/2 devices when this situation
> > >> > happen. Mario also told me that Windows is doing this action.
> > >>
> > >> Yeah, I remember fun with Inspiron 8100 - when you dock it it woudl
> > >> silently switch Synaptics touchpad into standard mode and it would not
> > >> come back as Synaptics until you disconnect. And there was no
> > >> notification to the kernel as far as I could tell.
> > >>
> > >> It could be that we need to monitor dock events and then kick reconnect
> > >> of serio port, either from userspace via udev (I think that would be
> > >> preferred), or in kernel.
> > >>
> > >> >
> > >> > Every time when I connect external PS/2 keyboard to dock I see this
> > >> > message in dmesg:
> > >> >
> > >> > Spurious ACK... Some program might be trying to access hardware directly.
> > >> >
> > >> > I see it also every time when I dock laptop into docking station (to
> > >> > which is keyboard already connected). And it happens also when I connect
> > >> > external PS/2 mouse to dock.
> > >> >
> > >> > Dmitry, how to handle this situation to re-initialize psmouse.ko when
> > >> > external PS/2 device is connected to Dell E docking station? According
> > >> > to Mario, this is how Dell Embedded Controller is designed and suppose
> > >> > how OS should work with it.
> > >> >
> > >> > Manually rmmoding and modprobing for every docking/undocking laptop is
> > >> > not ideal solution.
> > >> >
> > >> > Could it be possible to use that Spurious ATKBD_RET_ACK from atkbd.c be
> > >> > handled on Dell systems (probably via DMI) as an event to reset and
> > >> > reinitialize all PS/2 devices?
> > >>
> > >> So we need to figure out what exactly we are getting from the docking
> > >> station in this case. We do try to handle the new device 0xaa 0x00
> > >> announcements:
> > >
> > > Docking station itself won't have sent any events.  The PS2 ports in it
> > > are electrically wired to the external PS2 pins in the docking adapter on
> > > the system.
> > >
> > > System EC is what will be sending any PS2 events.
> > 
> > OK, it does not matter from the input layer POW, if they are PS/2
> > events they should be coming from i8042.

Dell EC sends reset to touchpad, not to kernel.

> > >
> > >>
> > >>       /* Check if this is a new device announcement (0xAA 0x00) */
> > >>       if (unlikely(psmouse->packet[0] == PSMOUSE_RET_BAT && psmouse-
> > >> >pktcnt <= 2)) {
> > >>               if (psmouse->pktcnt == 1) {
> > >>                       psmouse->last = jiffies;
> > >>                       goto out;
> > >>               }
> > >>
> > >>               if (psmouse->packet[1] == PSMOUSE_RET_ID ||
> > >>                   (psmouse->protocol->type == PSMOUSE_HGPK &&
> > >>                    psmouse->packet[1] == PSMOUSE_RET_BAT)) {
> > >>                       __psmouse_set_state(psmouse, PSMOUSE_IGNORE);
> > >>                       serio_reconnect(serio);
> > >>                       goto out;
> > >>               }
> > >>
> > >> ...
> > >>
> > >> I am not sure where the "spurious ACK comes from". Can you enable i8042
> > >> debug before trying to dock and capture the data stream from the mouse?
> > >>
> > >
> > > The system EC has reset PS2 devices (but AFAIK kernel won't have seen this
> > > communication).
> > 
> > So what kind of communication does EC send when docking? It sounds it
> > is completely out of band from PS/2 connection.
> 
> Yes it's out of band from PS/2 connection OS sees.  However as Pali has 
> mentioned this issue will happen even if already docked but you plug in
> PS/2 keyboard.
> 
> It will probably be clearer to you what OS has seen from this when Pali
> shares the captured data stream.

Currently I'm not near my docking station, so cannot do testing.

But in logs I can dig these lines which appeared every time after
putting notebook into dock (which has PS/2 keyboard connected):

kernel: [20127.033965] atkbd serio0: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly.
kernel: [20127.076030] acpi PNP0401:00: Already enumerated
kernel: [20127.083088] acpi PNP0501:00: Still not present
kernel: [20127.087042] acpi device:41: Cannot transition to power state D3hot for parent in (unknown)

And sometimes after 1-5s I see Spurious event again:

kernel: [20128.325569] atkbd serio0: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly.

-- 
Pali Rohár
pali.rohar@gmail.com