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From: Sascha Hauer <s.hauer@pengutronix.de>
To: "Eric Bénard" <eric@eukrea.com>
Cc: barebox@lists.infradead.org
Subject: Re: 800x480 Display broken on i.MX25 with MMU
Date: Wed, 18 Apr 2012 09:05:17 +0200	[thread overview]
Message-ID: <20120418070517.GK3852@pengutronix.de> (raw)
In-Reply-To: <20120418004139.4bdc7da1@eb-e6520>

On Wed, Apr 18, 2012 at 12:41:39AM +0200, Eric Bénard wrote:
> Hi,
> 
> on an i.MX25, it seems that 3100ea14668853aeedae85ec83e3536b59ba7728
> broke framebuffer usage with a 800x480 display when MMU is enabled :
> about 1/4 of the display (at the bottom) is garbage.
> 
> v2011.08.0 : it works fine
> 
> v2011.09.0 : it fails
> 
> disabling MMU makes it work again in v2011.09.0
> 
> then in v2011.09.0 it works with MMU enabled after reverting the
> following commits :
> 43ebdba64a6e1c12fe58aa57e905cfdcef922126
> 56c379160b9f0b52efcaaefce9adb6121d5865d7
> a6c333c7f2dbe49189dd5343da3c921659e88cbf
> 3100ea14668853aeedae85ec83e3536b59ba7728
> 
> So it seems something was broken during MMU rework and I don't yet know
> what : Sascha do you have an idea ?

What is the address of your framebuffer memory? The LCDC has a nasty
limitation, the DMA controller can only access 4MB, the other address
lines are fix. This means that you can't cross a 4MB boundary with the
framebuffer. Currently this case is not caught anywhere.

Sascha


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      reply	other threads:[~2012-04-18  7:05 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-17 22:41 Eric Bénard
2012-04-18  7:05 ` Sascha Hauer [this message]

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