Bug 186181

Summary:	long suspend/resume latency because of no type cover support - MS Surface Pro 4
Product:	Drivers	Reporter:	Zhang Rui (rui.zhang)
Component:	Input Devices	Assignee:	drivers_input-devices
Status:	RESOLVED CODE_FIX
Severity:	normal
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	All	Subsystem:
Regression:	No	Bisected commit-id:
Bug Depends on:
Bug Blocks:	178231
Attachments:	analyze_suspend output with type cover attached analyze_suspend output without type cover attached

Description Zhang Rui 2016-11-01 06:53:35 UTC

First of all, MS Surface Pro 4 type cover does not work if boot with upstream kernel. A similar problem is reported at bug #135561, with a patch to enable type cover. But it seems that nobody takes care of that patch.

Second, if I boot with type cover attached, it is enumerated as usb 1-7, which takes more than 10 seconds to suspend and more than 5 seconds to resume.

Comment 1 Zhang Rui 2016-11-01 06:54:23 UTC

Created attachment 243381 [details]
analyze_suspend output with type cover attached

Comment 2 Zhang Rui 2016-11-01 06:55:59 UTC

Created attachment 243391 [details]
analyze_suspend output without type cover attached

As a comparison, this is the analyze_suspend output if I suspend/resume the system without type cover attached.

Comment 3 Zhang Rui 2016-12-01 11:18:38 UTC

patch to support surface pro 4 type cover is sent at
https://patchwork.kernel.org/patch/9455863/

this patch also fixes the suspend/resume latency issue.

Comment 4 Zhang Rui 2016-12-12 05:58:33 UTC

confirmed the problem has been fixed in HID for-next branch.