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

On Monday 07 May 2018 12:33:06 Dmitry Torokhov wrote:

On Mon, May 07, 2018 at 10:44:31AM +0200, Pali Rohár wrote:

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On Sunday 06 May 2018 15:47:33 Pali Rohár wrote:

quoted

On Thursday 01 February 2018 11:29:45 Dmitry Torokhov wrote:

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Hi Pali,

On Wed, Jan 24, 2018 at 11:41:21AM +0100, Pali Rohár wrote:

quoted

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.

quoted

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.

Info about PS/2 mouse:

In case I have laptop already docked and just connect PS/2 mouse there
is absolutely no i8042 event.

To check that mouse is worked I clicked button and then in dmesg
appeared:

[ 3945.481403] i8042: [986322] 09 <- i8042 (interrupt, 1, 12)
[ 3945.482486] i8042: [986323] 00 <- i8042 (interrupt, 1, 12)
[ 3945.483667] i8042: [986323] 00 <- i8042 (interrupt, 1, 12)
[ 3945.483917] input: PS/2 ALPS Mouse as /devices/platform/i8042/serio1/input/input36
[ 3945.594926] i8042: [986351] 08 <- i8042 (interrupt, 1, 12)
[ 3945.596062] i8042: [986351] 00 <- i8042 (interrupt, 1, 12)
[ 3945.597203] i8042: [986351] 00 <- i8042 (interrupt, 1, 12)

So we have no way to detect when external PS/2 mouse was connected to
dock. But ALPS driver can deal with it and process these mouse events.

And when I have already connected PS/2 mouse to the dock and I'm just
putting laptop into dock, then I get following events:

[ 4336.481381] i8042: [1084079] fa <- i8042 (interrupt, 0, 1)
[ 4336.481388] atkbd serio0: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly.
[ 4337.653275] i8042: [1084372] ed -> i8042 (kbd-data)

I wonder where this "set leds" command is coming from and where is the
parameter... Can you add some more tracing? And maybe boot with
libps2.dyndbg=+pf

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[ 4337.949198] i8042: [1084446] fa <- i8042 (interrupt, 0, 1)
[ 4337.949202] atkbd serio0: Spurious ACK on isa0060/serio0. Some program might be trying to access hardware directly.
[ 4338.623167] i8042: [1084615] ed -> i8042 (kbd-data)

So again, no event from mouse, just from keyboard.

Note that in these tests I have disconnected my PS/2 keyboard from
dock.

So I guess you could write a platform driver that would install i8042
filter on Dell laptops/portables, monitor keyboard data stream and kick
of rescans on serio ports.

Ok. dell-laptop.ko already installs i8042 filter, so it could be
extended.

How can such dell-laptop.ko driver instruct serio0/1 devices to
reinitialize bound drivers (atk and psmouse, probably other)?

The problem is filter gets "serio" so you do
not really know whether ACK is spurious or not.

It is possible to extend i8042/serio driver to provide information via
i8042 filter callback if ACK is spurious or not?

And I would really
prefer keeping this crap out of atkbd proper... And all of this is racy
as hell. What happens if we get keyboard reconnected as we reinitialize
it?

Do not know, such race conditions are hard to test as you need correct
timing. And doing connecting/disconnecting PS/2 cable from dock together
with laptop docking/undocking cannot be done reliable for less then 5s
(need to press two buttons, take/unplug laptop + reconnecting PS/2 slot)
so hard to simulate race condition.

Plus we do not know what is that Dell EC doing with PS/2 data...

Mario, how does Windows driver know when it should send "vendor"
commands to reinitialize peripherals?

Thanks.

-- 
Pali Rohár
pali.rohar@gmail.com