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dm: virtio-input: ignore all MSC events from FE 

EV_MSC is configured as INPUT_PASS_TO_ALL in input driver. There is
a loop in the use case of virtio-input. They should not be forwarded
back to BE since they have already been sent to native driver before
sending to FE.

Tracked-On: #2006
Signed-off-by: Jian Jun Chen <jian.jun.chen@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
This commit is contained in:
Jian Jun Chen 2018-12-07 15:57:32 +08:00 committed by wenlingz
parent 19fb5fa03c
commit 2ef06450dc
1 changed files with 8 additions and 12 deletions
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20
devicemodel/hw/pci/virtio/virtio_input.c
View File

@ -214,23 +214,19 @@ virtio_input_ignore_event(struct virtio_input_event *event)
if (!event)
return true;
/* kernel commit 29cc309d8bf19a36c5196bf626662319af6e3c0b
* (HID: hid-multitouch: forward MSC_TIMESTAMP)
* since kernel 4.15
* (EV_MSC, MSC_TIMESTAMP) is added to each frame just before
* the SYN event. EV_MSC is configured as INPUT_PASS_TO_ALL.
* In the use case of virtio-input, there is a loop as follows:
* - A mt frame with (EV_MSC, MSC_TIMESTAMP) is passed to FE.
* - FE will call virtinput_status to pass (EV_MSC, MSC_TIMESTAMP)
* back to BE.
* - BE writes this event to evdev. Because (EV_MSC, MSC_TIMESTAMP)
/*
* EV_MSC is configured as INPUT_PASS_TO_ALL. In the use case of
* virtio-input, there is a loop as follows:
* - A mt frame with (EV_MSC,*,*) is passed to FE.
* - FE will call virtinput_status to pass (EV_MSC,*,*) back to BE.
* - BE writes this event to evdev. Because (EV_MSC,*,*)
* is configured as INPUT_PASS_TO_ALL, it will be written into
* the event buffer of evdev then be read out by BE without
* SYN followed.
* - Each mt frame will introduce one (EV_MSC, MSC_TIMESTAMP).
* - Each mt frame will introduce one (EV_MSC,*,*).
* Later the frame becomes larger and larger...
*/
if ((event->type == EV_MSC) && (event->code == MSC_TIMESTAMP))
if (event->type == EV_MSC)
return true;
return false;
}