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Message-ID: <Pine.LNX.4.44L0.1408271035351.1460-100000@iolanthe.rowland.org>
Date: Wed, 27 Aug 2014 10:38:12 -0400 (EDT)
From: Alan Stern <stern@...land.harvard.edu>
To: Gavin Guo <gavin.guo@...onical.com>
cc: linux-usb@...r.kernel.org,
linux-kernel <linux-kernel@...r.kernel.org>,
Anthony Wong <anthony.wong@...onical.com>,
YK <yk@...onical.com>
Subject: Re: About the reboot hang issue with EHCI driver on the Baytrail
platform
On Wed, 27 Aug 2014, Gavin Guo wrote:
> > Still, why not use the BIOS setting to disable EHCI?
>
> It's hardware enablement policy. By default, we can't change the BIOS
> setting to make the bug disappear until we find out the bug is due to
> BIOS's bug. Add kernel parameters is the temporary solution for the
> platform can ship. And if the bug is from kernel, we need to send
> patches to upstream and pull back to Ubuntu kernel or send to Ubuntu
> Kernel directly if it's a trivial solution like adding device id.
> However, as you said, in this case about the bug the root may be from
> BIOS code. So, we can coordinate with the OEM BIOS team to modify the
> default BIOS setting.
There is no doubt that the BIOS is buggy. Your log contains this line:
[ 2.804205] pci 0000:00:1d.0: EHCI: BIOS handoff failed (BIOS bug?) 01010001
The only way that can happen is if the BIOS isn't working right.
However, this may be a different bug from the crashes you've been
seeing.
Alan Stern
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