Re: Missing release event for Synaptics touchscreen

[Martin Kepplinger <martin.kepplinger@ginzinger.com>]

On 2017-05-11 12:12, Arek Burdach wrote:
>
>
> On 11.05.2017 11:48, Martin Kepplinger wrote:
>>
>> On 2017-05-10 11:36, Arek Burdach wrote:
>>> Hi Andrew,
>>>
>>> On 10.05.2017 01:47, Andrew Duggan wrote:
>>>> HI Arek,
>>>>
>>>> On 05/09/2017 04:17 PM, Arek Burdach wrote:
>>>>> Hi,
>>>>>
>>>>> I've tried described by you solution:
>>>>>
>>>>> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
>>>>> index 37084b645785..81f271554b6c 100644
>>>>> --- a/drivers/hid/hid-core.c
>>>>> +++ b/drivers/hid/hid-core.c
>>>>> @@ -2510,6 +2510,7 @@ static const struct hid_device_id
>>>>> hid_ignore_list[] = {
>>>> You need to add this to the hid_have_special_driver[] and not the
>>>> hid_ignore_list[].
>>> Nice score for me - two lines and one bug :-)
>>>
>>>> But, if you do success in binding hid-rmi to a touchscreen it won't
>>>> work. The firmware between touchpads and touchscreens are different
>>>> enough that the hid-rmi driver will be looking for data which does not
>>>> exist in touchscreen's HID report. These differences also mean that it
>>>> really isn't a good idea to try to support touchscreens with hid-rmi.
>>>> It would actually result in more transactions and be less efficient
>>>> then simply using hid-multitouch. That's why hid-core checks for the
>>>> HID_SCAN_FLAG_GD_POINTER in an attempt to make sure it's binding to a
>>>> touchpad and not a touchscreen.
>>> It was just like you predict. On rmi, after first tap on screen, hidraw
>>> produced infinite number of events and it is not usable anymore.
>>>
>>>
>>>>> On 09.05.2017 16:02, Benjamin Tissoires wrote:
>>>>>> On Tue, May 9, 2017 at 2:51 PM, Arek Burdach
>>>>>> <arek.burdach@gmail.com> wrote:
>>>>>>> On 09.05.2017 14:20, Benjamin Tissoires wrote:
>>>>>>>> On Tue, May 9, 2017 at 11:20 AM, Arek Burdach
>>>>>>>> <arek.burdach@gmail.com>
>>>>>>>> wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> Thank you for response.
>>>>>>>>>
>>>>>>>>> On 09.05.2017 10:35, Benjamin Tissoires wrote:
>>>>>>>>>> On Sat, May 6, 2017 at 9:28 PM, Arek Burdach
>>>>>>>>>> <arek.burdach@gmail.com>
>>>>>>>>>> wrote:
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> A week ago I've reported a bug:
>>>>>>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=195625 Is there
>>>>>>>>>>> anybody
>>>>>>>>>>> that
>>>>>>>>>>> can
>>>>>>>>>>> help me with it?
>>>>>>>>>> I can have a look at it.
>>>>>>>>>> Please attach the full outputs of hid-recorder and evemu-record
>>>>>>>>>> in the
>>>>>>>>>> bugs, or it'll be difficult for us to debug it.
>>>>>>>>> I've attached full logs for two situations. More details in the
>>>>>>>>> issue.
>>>>>>>> Thanks, looks like a firmware issue (I'll comment in the bug).
>>>>>>> Sorry for my noob questions, but do you suggest that it can't be
>>>>>>> fixed by
>>>>>>> changes in kernel modules and I need to report it to the
>>>>>>> manufacturer?
>>>>>> Yes. Though Andrew, in CC, works for Synaptics and might give us
>>>>>> some pointers.
>>>>>>
>>>>>>> If it so, do you have an idea why it works well on Windows? Do they
>>>>>>> have
>>>>>>> some strange hacks in their drivers?
>>>>>> I have no ideas how well it works under Windows, and I have no ideas
>>>>>> if there are some strange hacks in the Windows nor in the Syanptics
>>>>>> driver (I would assume so).
>>>>>>
>>>> We don't provide any drivers for touchscreens on Windows. So I don't
>>>> know how Microsoft is handling a situation like this.
>>> Do you know what should be changed in firmware to make hid-touchscreen
>>> driver works correctly? Or maybe you know someone who is responsible for
>>> firmware for this device and whom I can call to gather this information?
>>>
>> In case there *really* is broken firmware out there, we can specifically
>> identify via struct input_id's version number for example,
> I thought that Benjamin identified this as a broken firmware. I've
> attached hidraw log in the issue and there is no release event, so it
> looks like a firmware bug. How do you suggest to handle this situation
> in kernel? We can identify the device but what to do next if we have no
> information if user released finger or not?
>
>> I want to
>> point out that I would accept adding a workaround in tslib's input-raw
>> module ( http://tslib.org ) if it won't be done in the kernel.
>>
>> So, in case you can and want to use tslib as a workaround here, feel
>> free to have a look and send the patches that make input-raw.c work for
>> you over there.
> I want to be as handy as I can but I'm not sure how tslib could help in
> this situation. If we have too much data, it can filter out unnecessary
> events but I don't think that it can help when there is lack of events
> or I'm missing something?

Might as well be, I might not have thought it all through, but in
tslib's module_raw input you can can get totally creative: Why not start
*every* sync frame with BTN_TOUCH 1 and end it with BTN_TOUCH 0? You
*are* able to add stuff. Filters don't usually do it though.

                        martin


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