Re: [PATCH v2] HID: multitouch: Fetch feature reports on demand for Win8 devices

[Jiri Kosina]

On Wed, 7 Oct 2015, Mika Westerberg wrote:

> Some newer Intel Skylake based Dell laptops with Win8 precision touchpad
> fail when initial feature reports are fetched from it. Below is an example
> output with some additional debug included:
> 
>  i2c_hid i2c-DLL0704:01: Fetching the HID descriptor
>  i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=20 00
>  i2c_hid i2c-DLL0704:01: HID Descriptor: 1e 00 00 01 99 02 21 00 24 ...
>  ...
>  i2c_hid i2c-DLL0704:01: i2c_hid_get_report
>  i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 38 02 23 00
>  i2c_hid i2c-DLL0704:01: report (len=4): 04 00 08 05
>  i2c_hid i2c-DLL0704:01: report id 13
>  i2c_hid i2c-DLL0704:01: i2c_hid_get_report
>  i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 3d 02 23 00
>  i2c_hid i2c-DLL0704:01: failed to retrieve report from device.
>  i2c_hid i2c-DLL0704:01: report id 7
>  i2c_hid i2c-DLL0704:01: i2c_hid_get_report
>  i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 37 02 23 00
>  i2c_hid i2c-DLL0704:01: report (len=259): 03 01 07 fc 28 fe 84 40 ...
>  i2c_hid i2c-DLL0704:01: report id 4
>  i2c_hid i2c-DLL0704:01: i2c_hid_get_report
>  i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 34 02 23 00
> 
> We manage to fetch few reports but then the touchpad dies:
> 
>  i2c_designware i2c_designware.1: i2c_dw_handle_tx_abort: lost arbitration
>  i2c_hid i2c-DLL0704:01: failed to retrieve report from device.
> 
> it eventually pulls the whole I2C bus low:
> 
>  i2c_designware i2c_designware.1: controller timed out
>  i2c_hid i2c-DLL0704:01: failed to set a report to device.
> 
> Fix this by preventing initial feature report retrieval for Win8 devices.
> Instead we fetch reports as needed in mt_feature_mapping(). This prevents
> fetching reports which might cause problems with the device in question.
> 
> Suggested-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> ---
> Added check for MT_CLS_WIN_8 so that the fix is only done for real Win8
> devices.

This is now in hid.git#for-4.4/multitouch. Thanks everybody,

-- 
Jiri Kosina
SUSE Labs

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