Re: Missing release event for Synaptics touchscreen

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On 11.05.2017 13:22, Martin Kepplinger wrote:

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@xxxxxxxxx> wrote:
On 09.05.2017 14:20, Benjamin Tissoires wrote:
On Tue, May 9, 2017 at 11:20 AM, Arek Burdach
<arek.burdach@xxxxxxxxx>
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@xxxxxxxxx>
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.
If I end every BTN_TOUCH 1 with BTN_TOUCH 0 after a while, we won't be able to do real drags. Of course we can introduce timeout for cursor move events, but this timeout would be extremely long because users quite often put finger on touchscreen and after a longer delay start dragging. I'm not sure that this workaround would be better than current situation.
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