Re: [PATCH] HID: Add driver for acer keybard with broken rdesc

[Andrew Duggan <aduggan@synaptics.com>]

On 02/17/2015 04:30 AM, Jiri Kosina wrote:
> On Thu, 29 Jan 2015, linux@simon-woerner.de wrote:
>
>> From: Simon Wörner <mail@simon-woerner.de>
>>
>> HID: Add driver for acer keybard with broken rdesc
> Hi Simon,
>
> to make sure proper device <-> driver binding is performed, you also have
> to add device ID to the hid_have_special_driver[] array.
>
I have been meaning to respond to this patch. Unfortunately, simply 
adding this driver to the hid_have_special_driver[] list will prevent 
hid-multitouch from binding to the touchpad which shares the same vid 
and pid. My suggestion would be to create a new scan_flag for 
GD_KEYBOARD and to add to the code in hid_scan_collection() which scans 
the GENDESK usages. Similar to the code which is searching for 
HID_GD_POINTER. Then in hid_scan_report() we could assign a group for 
this driver based on the pid and the GD_KEYBOARD scan flag in the vendor 
handling code.

I can help out with implementing this part of the patch if there aren't 
any other suggestions. Adding a new group and more code to the 
hid_scan_report() vendor handling code is definately not ideal. But, I 
am not sure of a better way of binding different sub drivers to devices 
with the same vid and pid.

An alternative would be to have hid-rmi handle all Synaptics touchpads, 
even the ones which currently use hid-multitouch. Then the keyboard 
report descriptor fixup could just be handled in hid-rmi. Accessing the 
finger data via rmi mode would also have the benefit of being able to 
report events which are currently not supported by the PTP collection 
(ie ABS_MT_PRESSURE, ABS_MT_TOUCH_MAJOR/MINOR). The touchpads which 
currently use hid-multitouch report finger data a little differently 
then the ones currently using hid-rmi so there is some work which would 
need to be done to add support for them in hid-rmi.

Andrew
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