linux-kernel - RE: Dell docking station & Dell Embedded Controller & PS/2 devices

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Date:   Mon, 7 May 2018 20:30:28 +0000
From:   <Mario.Limonciello@...l.com>
To:     <pali.rohar@...il.com>
CC:     <dmitry.torokhov@...il.com>, <linux-input@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: RE: Dell docking station & Dell Embedded Controller & PS/2 devices

> -----Original Message-----
> From: Pali Rohár [mailto:pali.rohar@...il.com]
> Sent: Monday, May 7, 2018 3:28 PM
> To: Limonciello, Mario
> Cc: dmitry.torokhov@...il.com; linux-input@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: Re: Dell docking station & Dell Embedded Controller & PS/2 devices
> 
> On Monday 07 May 2018 20:18:30 Mario.Limonciello@...l.com wrote:
> > > > > 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. The problem is filter gets "serio" so you do
> > > > > not really know whether 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?
> > > >
> > > > If it's done as a platform driver I would suspect it's possible to tell whether
> > > > a dock is connected to at least give you some heuristic here to have a better
> > > > guess whether it's spurious.
> > >
> > > Apparently checking for docking station is not enough. There are also
> > > Dell Legacy Extenders (or how it is called) which exports internal PS/2,
> > > Parallel and Serial Ports. It is also connecting to bottom of laptop.
> > > But currently I do not have them for testing.
> > >
> > > > Pali on your system that supports this dock, check and see how many
> > > > System Enclosure SMBIOS tables (structure type 03) are present.
> > >
> > > Do you mean DMI type 3 structure? Here is something from dmidecode:
> > >
> > > Handle 0x0003, DMI type 3, 22 bytes
> > > Chassis Information
> > >         Manufacturer: Dell Inc.
> > >         Type: Laptop
> > >         Lock: Not Present
> > >         Version: Not Specified
> > >         Serial Number: --REMOVED--
> > >         Asset Tag: Not Specified
> > >         Boot-up State: Safe
> > >         Power Supply State: Safe
> > >         Thermal State: Safe
> > >         Security Status: None
> > >         OEM Information: 0x00000000
> > >         Height: Unspecified
> > >         Number Of Power Cords: 1
> > >         Contained Elements: 0
> > >         SKU Number: To be filled by O.E.M.
> > >
> > > But probably you mean something different?
> >
> > Plug in your dock before you boot up and see if you have a second structure like
> > that type produced.
> 
> I already started docked laptop via dock power button. And in dmidecode
> output is only one DMI type 3 block.
> 
> > If not, then I guess this isn't a reliable way to find the dock
> > on that system and I'll have to see if there is another.
> 
> Seems not. Also detection of dock should work also when you connect
> laptop at system runtime, not only when connected prior to booting.
> 

The items that show up in this structure are supposed to be dynamic
values but static addresses.  I was asking to check before bootup in 
case this was a problem of Linux caching SMBIOS table information once.
The values I was referring to might be for older generation dock though,
I'll see if I can find anything else you can check.