Jian Jun Chen 94dadc1d14 dm: virtio-input: ignore MSC_TIMESTAMP from guest ...

(EV_MSC, MSC_TIMESTAMP) is added to each frame just before the
SYN event since kernel 4.15. 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)
  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).
  Later the frame becomes larger and larger...

This patch fixed above issue by ignoring MSC_TIMESTAMP from guest.
Besides that timestamp is added for every status event from guest
before writing to evdev.

Tracked-On: #1670
Signed-off-by: Jian Jun Chen <jian.jun.chen@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>

2018-11-02 13:42:43 +08:00

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