Date:   Fri, 10 Mar 2017 10:56:33 -0800
From:   Andrew Duggan <aduggan@...aptics.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-input@...r.kernel.org>
Subject: Re: [PATCH 0/8] PS

On 03/10/2017 09:52 AM, Dmitry Torokhov wrote:
> On Fri, Mar 10, 2017 at 04:57:35PM +0100, Benjamin Tissoires wrote:
>> Hi Dmitry,
>>
>> On Mar 09 2017 or thereabouts, Dmitry Torokhov wrote:
>>> Hi,
>>>
>>> This is refresh of Benjamin's patches trying to bridge PS/2 and SMbus
>>> devices for better support of Synaptics RMI4 touchpads (and Elans later).
>> Thanks!
>>
>> I have some issues/comments and am still working on those. Here are some
>> general comments:
>>
>>> The main difference is that we do not have platform device, as it only
>>> adds another indirection level, and have psmouse create SMBus companion
>> The purpose of having the platform device was to not have dependency
>> between psmouse and I2C. Right now I think that patch 6/8 will fail to
>> compile if I2C=m and PSMOUSE=y (I may be wrong).
> This is taken care by the following guards in users if MOUSE_PS2_SMBUS:
>
> depends on I2C=y || I2C=MOUSE_PS2
>
> I am perfectly fine to tie psmouse to I2C *core*, we do not need to have
> adapters loaded for it to work (hopefully).
>
>>> directly. Because serio ports complete registration asynchronously, we do
>>> not deadlock on psmouse_mutex when even if we have a pass-through port.
>>> (Frankly we need to revisit this whole serio and psmouse thing, use of
>>> global serio_mutex and psmouse_mutex is hurting us; they were needed when
>>> driver core could not recursively iterate over device and driver lists).
>> Agree, this is a giant PITA.
>>
>>> We also do not allow overriding serio driver, instead we teach psmouse
>>> about "special" devices and let it continue own the serio port and make
>>> sure nobody else touches it.
>>>
>>> To work around issue with psmouse_reconnect() running sometimes too late,
>>> we add "fast reconnect" option to serio. Not too pretty, but gets the job
>>> done. We may need to revisit whole serio PM story later and stop "cheating"
>>> and pretending that device is resumed when it is not, but for that we need
>>> to teach PM core about devices that are OK not to wait for before resuming
>>> userspace. Anyway, much bigger topic for later.
>> I thought there was already the ability to say that a driver needs to be
>> run in a different thread for PM functions (IIRC i2c-hid uses
>> device_enable_async_suspend(&client->dev); and this "should" do the
>> trick).
> The issue is that currently asynchronous resume still has to complete
> before we start resuming userspace, as PS/2 is way too slow. So the
> current solution marks device as resumed right away, and mouse may
> become responsive 2 seconds later, but that is good as we do not idly
> sit and wait but have userspace start turning on the screen and do other
> useful stuff. Maybe user can already start typing their password into
> screen locker.
>
> We would need to give a way to drivers to indicate to PM core just how
> asynchronous our resume can be.
>
>>> This seems to be working on X1 Carbon and also not breaking my HP 1040 with
>>> forcepad (unfortunately it seems to be using some other SMBus controller
>>> for connecting Synaptics, as I see nothing at 0x2c when loading i2c-i801).
>> Well, on my T450, the SMBus connection is dead too. I can't seem to talk
>> to the device at all. This happens when the firmware believes it needs
>> to stay on PS/2 and gets completely deaf to I2C. I solved this by
>> calling psmouse_deactivate(), but this time, it looks like some other
>> function needs to be called.
>>
>> I'll keep investigating and report back.
> I've heard a rumors that HP 1020 uses a Microtech SMbus controller for
> its touchpad, it could be that 1040 is similar.
>
> When your SMBus connection is dead do you see anything on the bus? At
> that address? Or it is completely unresponsive?

Try the I2C address 0x20 for the HP forcepad. I have gotten previous 
versions of Benjamin's SMBus patches working on a similar system. It is 
a HP Elitebook Folio 940 and the forcepad was at address 0x20 and it was 
on the i801 bus. The HP 1020 does have a microchip I2C controller, but 
thats connected to a HID / I2C touchpad. The 1020 was a one off so the 
1040 should be the more common SMBus implementation.

I also have not been able to get this patch series to successfully 
switch over to SMBus mode. But, I have not had a chance to do anything 
besides apply the patches and build. This is the output from a Lenovo W541:

[    9.674826] psmouse serio1: synaptics: queried max coordinates: x 
[..5676], y [..4758]
[    9.705273] psmouse serio1: synaptics: queried min coordinates: x 
[1266..], y [1096..]
[    9.705276] psmouse serio1: synaptics: Trying to set up SMBus access
[    9.707946] psmouse serio1: synaptics: SMbus companion is not ready yet
[    9.764848] psmouse serio1: synaptics: Touchpad model: 1, fw: 8.1, 
id: 0x1e2b1, caps: 0xf003a3/0x943300/0x12e800/0x10000, board id: 3053, 
fw id: 2560
[    9.764853] psmouse serio1: synaptics: serio: Synaptics pass-through 
port at isa0060/serio1/input0
[   10.418268] psmouse serio2: trackpoint: IBM TrackPoint firmware: 
0x0e, buttons: 3/3
...
[   27.112954] psmouse serio1: synaptics: queried max coordinates: x 
[..5676], y [..4758]
[   27.142555] psmouse serio1: synaptics: queried min coordinates: x 
[1266..], y [1096..]
[   27.142559] psmouse serio1: synaptics: Trying to set up SMBus access
[   27.169776] psmouse serio1: synaptics: SMbus companion is not ready yet
[   27.226071] psmouse serio1: synaptics: Touchpad model: 1, fw: 8.1, 
id: 0x1e2b1, caps: 0xf003a3/0x943300/0x12e800/0x10000, board id: 3053, 
fw id: 2560
[   27.226087] psmouse serio1: synaptics: serio: Synaptics pass-through 
port at isa0060/serio1/input0
[   27.880282] psmouse serio3: trackpoint: IBM TrackPoint firmware: 
0x0e, buttons: 3/3

Andrew

> Thanks.
>

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