Re: Dell docking station & Dell Embedded Controller & PS/2 devices

["Pali Rohár" <pali.rohar@gmail.com>]

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On Thursday 01 February 2018 11:29:45 Dmitry Torokhov wrote:
> 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:
> 
> 	/* 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?
> 
> Thanks.
> 

Hi Dmitry!

I enabled unmask_kbd_data and debug and here is output from dmesg.

echo Y > /sys/module/i8042/parameters/debug
echo Y > /sys/module/i8042/parameters/unmask_kbd_data

PS/2 keyboard is already connected in dock and laptop was just docked:

[25461.552314] i8042: [6365474] fa <- i8042 (interrupt, 0, 1)
[25461.552319] atkbd serio0: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly.
[25462.707296] i8042: [6365763] ed -> i8042 (kbd-data)
[25462.851289] i8042: [6365799] fa <- i8042 (interrupt, 0, 1)
[25462.851303] i8042: [6365799] 00 -> i8042 (kbd-data)
[25462.858437] i8042: [6365801] fa <- i8042 (interrupt, 0, 1)
[25462.869512] i8042: [6365804] fa <- i8042 (interrupt, 0, 1)
[25462.869517] atkbd serio0: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly.
[25463.670515] i8042: [6366004] ed -> i8042 (kbd-data)
[25463.670647] i8042: [6366004] fa <- i8042 (interrupt, 0, 1)
[25463.670655] i8042: [6366004] 02 -> i8042 (kbd-data)
[25463.676769] i8042: [6366005] fa <- i8042 (interrupt, 0, 1)


Laptop is docked and PS/2 keyboard was just connected:

[26571.014368] i8042: [6642848] fa <- i8042 (interrupt, 0, 1)
[26571.014380] atkbd serio0: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly.


In both cases there is no events from touchpad, only from keyboard. So
Dell EC silently reset PS/2 touchpad when PS/2 keyboard is attached.

So I think we should capture 0xFA and on Dell machines we should
reinitialize PS/2 drivers. As there is really nothing more then 0xFA.

-- 
Pali Rohár
pali.rohar@gmail.com

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