Linaro Android

Serial console doesn't work reliably on vexpress with KitKat

Bug #1254738 reported by Tixy (Jon Medhurst)
10
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Linaro Android
Fix Released
High
Tixy (Jon Medhurst)

Bug Description

On the majority of times I boot KitKat on vexpress the serial console doesn't accept any input.
I've never seen this issue with Jelly Bean even when running the same kernel as used on KitKat.

Tags: serial
Revision history for this message
vishal (vishalbhoj) wrote :

can you please share the bootlogs ?

Tixy (Jon Medhurst) (tixy)
Changed in linaro-android:
assignee: nobody → Tixy (Jon Medhurst) (tixy)
Revision history for this message
Tixy (Jon Medhurst) (tixy) wrote :

The reason this issue has shown up on KitKat is that there is a whole bunch of new kernel messages being output form 'healthd' which occur at the same time the same serial port is being initialised for the Android console. This has shown up a race condition in the serial driver which the attached patch fixes. (Unfortunately there may still be other issues of a similar nature lurking.)

We would probably avoid tripping over this serial port issue if we could silence the 'healthd' battery messages , which look ugly anyway and occur every minute after boot.

Revision history for this message
Tixy (Jon Medhurst) (tixy) wrote :

As the patch in comment #2 fixes the bug and is present in the latest build I'm marking this as Fix Committed

Changed in linaro-android:
status: New → Fix Committed
Revision history for this message
Tixy (Jon Medhurst) (tixy) wrote :

I should point out that this bug is not yet fixed in LSK.

Revision history for this message
Tixy (Jon Medhurst) (tixy) wrote :

A patch to mitigate this problem has been added to Android code [1] and so this bug should very rarely show even on kernels without the serial driver fix. (Like the LSK kernel which is still waiting for upstream comment/acceptance of the kernel fix [2].)

[1] http://review.android.git.linaro.org/#/c/10358/
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2013-December/217615.html

Naresh Kamboju (naresh-kamboju)
Changed in linaro-android:
status: Fix Committed → Fix Released
To post a comment you must log in.
This report contains Public information  
Everyone can see this information.
Subscribing...

Other bug subscribers

Remote bug watches

Bug watches keep track of this bug in other bug trackers.