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Re: Epson13806 performances on Pb1100

To: Karl Lessard <klessard@sunrisetelecom.com>
Subject: Re: Epson13806 performances on Pb1100
From: Dan Malek <dan@embeddededge.com>
Date: Wed, 8 Dec 2004 11:40:36 -0500
Cc: linux-mips@linux-mips.org, ppopov@embeddedalley.com
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On Dec 8, 2004, at 11:06 AM, Karl Lessard wrote:

Everything works fine, but for the speed. It seems that accessing the chip is
too slow for having high-graphic performances.

A couple of things.  First, the Epson controller is obsolete, I don't
know how much time is worth spending on the software.  If you
don't already have a system in production using it, there isn't
much sense spending time working with it.

Second, with the on-chip controller, I have experimented with
some different cache modes for the frame buffer access.  I
don't know if this applicable to the external 13806, but you
could try.  Alchemy has an application note on this, I believe,
but in any case, here is what I put into the au1100fb.c,
au1100fb_mmap() function:

pgprot_val(vma->vm_page_prot) &= ~_CACHE_MASK;
pgprot_val(vma->vm_page_prot) |= _CACHE_CACHABLE_CUW;

A similar kind of update is in the current CVS tree.

Fujitsu has a bunch of nice high performance embedded
graphics controllers for many different applications.


        -- Dan


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