linux-kernel - Re: [PATCH] TPM: Retry SaveState command in suspend path

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Date:	Wed, 17 Apr 2013 09:54:24 -0500
From:	Kent Yoder <shpedoikal@...il.com>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	Duncan Laurie <dlaurie@...omium.org>,
	Dirk Hohndel <dirk@...ndel.org>,
	Kent Yoder <key@...ux.vnet.ibm.com>,
	Luigi Semenzato <semenzato@...omium.org>,
	TPM Device Driver List <tpmdd-devel@...ts.sourceforge.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] TPM: Retry SaveState command in suspend path

On Tue, Apr 16, 2013 at 6:57 PM, Greg KH <gregkh@...uxfoundation.org> wrote:
> On Tue, Mar 19, 2013 at 10:00:02AM -0500, Kent Yoder wrote:
>> Hi Duncan,
>>
>> On Sun, Mar 17, 2013 at 4:56 PM, Duncan Laurie <dlaurie@...omium.org> wrote:
>> > If the TPM has already been sent a SaveState command before the driver
>> > is loaded it may have problems sending that same command again later.
>> >
>> > This issue is seen with the Chromebook Pixel due to a firmware bug in
>> > the legacy mode boot path which is sending the SaveState command
>> > before booting the kernel.  More information is available at
>> > http://crbug.com/203524
>> >
>> > This change introduces a retry of the SaveState command in the suspend
>> > path in order to work around this issue.  A future firmware update
>> > should fix this but this is also a trivial workaround in the driver
>> > that has no effect on systems that do not show this problem.
>>
>>   I'm not convinced that this needs to be upstream.  The simplest
>> route would seem to be to carry this out of tree until your firmware
>> is fixed.
>
> Really?  We have machines that we are using right now that need this fix
> in order to work properly.
>
> The kernel handles buggy firmware/bioses all the time, we need to work
> properly on all hardware, we can't count on a firmware update ever
> getting pushed out publically, and for those of us using this hardware,
> we want it to work.

  That makes sense -- on first read I thought this was an issue with
Chrome OS only.  I see now this is an issue with reinstalling other
OS's over Chrome.  I've staged this over here:

git://github.com/shpedoikal/linux.git tpmdd-04-17-13

and I'll push this to James later today.

Kent

> So, please accept this patch,
>
> thanks,
>
> greg l-h
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