Linux ARM-MSM sub-architecture
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From: Tomasz Sterna <tomek@xiaoka.com>
To: Daniel Walker <dwalker@codeaurora.org>
Cc: linux-arm-msm@vger.kernel.org, Bradley Smith <brad@brad-smith.co.uk>
Subject: Re: [PATCH] [Streak] Add workaround for TTY kernel OOPS at the cost of performance.
Date: Fri, 01 Oct 2010 10:52:56 +0200	[thread overview]
Message-ID: <1285923176.16981.53.camel@ubuntu> (raw)
In-Reply-To: <1285887854.14953.46.camel@c-dwalke-linux.qualcomm.com>

On czw, 2010-09-30 at 16:04 -0700, Daniel Walker wrote: 
> > Signed-off-by: Bradley Smith <brad@brad-smith.co.uk>
> > (cherry picked from commit 28d06a6366c851c6e0c5b954353bf82cb641d4e7)
> 
> Your submitting this for Bradley? If so you need to have a line like
> this at the top,

I am not exactly _submitting_ it. Bradley said this is a dirty
workaround and needs a real fix instead. This change just gave us
working kernel console.
I am rather pointing the problem and sharing the workaround.


> From: Bradley Smith <brad@brad-smith.co.uk>
> That denotes that your not the author of the commit..

I'm pretty new to git - sorry.
Yes, Bradley is the author of the patch. I only ported it to msm-2.6.35
from his android-msm-2.6.32 tree.

> Also this is against v2.6.36-rcX right ?

This is against msm-2.6.35 
> > +config MSM_FB_TTY_WORKAROUND
> > +	bool "Workaround TTY kernel OOPS at the cost of performance"
> > +	depends on FB_MSM
> > +	default n
> 
> We can't have this selectable , especially if the kernel will OOPS if
> it's off ..

As I mentioned - this is only a workaround of the problem. We turn it on
while debugging kernel boot, and off once it is working to get a better
performing fbcon for X11.


> I need a better description of the problem. What was the oops? This
> looks DMA related, is that accurate and could you expand on why DMA was
> causing a problem?

If you start an android-msm-2.6.29 or msm-2.6.35 (these are the ones I
tested) with MSM_FB driver compiled in and use 'console=tty' kernel
commandline option, kernel starts with proper console output on screen
and oopses in the middle of the process.
I don't know the exact nature of the problem. Maybe Brad would shed some
light.

If you're unable to reproduce the problem, I will rebuild the kernel
without the workaround and retype the OOPS message for you.


  reply	other threads:[~2010-10-01  8:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-30 22:42 [PATCH] [Streak] Add workaround for TTY kernel OOPS at the cost of performance Tomasz Sterna
2010-09-30 23:04 ` Daniel Walker
2010-10-01  8:52   ` Tomasz Sterna [this message]
2010-10-01 15:47     ` Daniel Walker
2010-10-01 20:07       ` Tomasz Sterna
2010-10-02  0:26         ` Daniel Walker
2010-10-01 21:11       ` Tomasz Sterna
     [not found]     ` <AANLkTimVpsmWLpXwuLyFgC3sOSMVCbF38DNRL13_5bgk@mail.gmail.com>
2010-10-02 10:14       ` Bradley Smith

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