From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wr-out-0506.google.com (wr-out-0506.google.com [64.233.184.235]) by ozlabs.org (Postfix) with ESMTP id BEE0DDDE18 for ; Tue, 21 Aug 2007 19:49:27 +1000 (EST) Received: by wr-out-0506.google.com with SMTP id 71so1188210wri for ; Tue, 21 Aug 2007 02:49:25 -0700 (PDT) Message-ID: <929bf310708210249x3cf8342aq4523d2a895d78eb@mail.gmail.com> Date: Tue, 21 Aug 2007 11:49:25 +0200 From: "Konstantin Boyanov" To: "Johan Borkhuis" Subject: Re: Driver for device behind a PCI-VME bridge In-Reply-To: <46CAA332.9060907@dutchspace.nl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_127555_31115001.1187689765534" References: <929bf310708200140w6efc57f6k81a1339845059e2d@mail.gmail.com> <46C954AA.7050609@dutchspace.nl> <929bf310708200158m3dab7669j56e4dbf2d84f17a@mail.gmail.com> <929bf310708210055k3970c3chfc097ff776af439a@mail.gmail.com> <929bf310708210056s2b699500x36c6b1ae83881496@mail.gmail.com> <46CAA332.9060907@dutchspace.nl> Cc: linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , ------=_Part_127555_31115001.1187689765534 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Hi again, I also work with devices on the VME bus. The approach we took is to map > all the devices into userspace, and use Xenomai for RT performance. This > avoids the need to write drivers for all the devices. The RT-performance > of Xenomai is quite good: the jitter on a timer-interrupt is always less > than 20usec, even under high load, where standard Linux only achieves > this in a no load situatieo, under high load standard Linux has a jitter > of over 10 msec. Good advice, I will investigate in this direction. The setup we choose was to have a RT-interrupt handler and a RT IOCTL > call "WAIT_FOR_INTERRUPT". This is a slightly modified version from the > Motorola driver (I guess that you also use the Tundra chipset to access > the VME-bus). Yes, I do. It is the Tsi148 in fact. I'll be interested to see some sample code of yours, if it doesn't violate some restrictions ofcourse. Here you can wait for a specific VME interrupt-level, and > it returns the vector number. So you can have several applications > connect to the same VME driver, but all on different levels. So, if I understand you correctly, you altered the Motorola driver in order for it to be able to communicate with user spae programms through Xenomai. Which version of Xenomai ws that? I tried to test Xemonai 2.0 on my setup but it iterfred somehow with SSH configuration and thats why i dropped it. Many thanks, Konstantin ------=_Part_127555_31115001.1187689765534 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline
 
Hi again,

I also work with devices on the VME bus. The approach we took is to map
all the devices into userspace, and use Xenomai for RT performance. This
avoids the need to write drivers for all the devices. The RT-performance
of Xenomai is quite good: the jitter on a timer-interrupt is always less
than 20usec, even under high load, where standard Linux only achieves
this in a no load situatieo, under high load standard Linux has a jitter
of over 10 msec.
 
Good advice, I will investigate in this direction.

The setup we choose was to have a RT-interrupt handler and a RT IOCTL
call "WAIT_FOR_INTERRUPT". This is a slightly modified version from the
Motorola driver (I guess that you also use the Tundra chipset to access
the VME-bus).
 
Yes, I do. It is the Tsi148 in fact. I'll be interested to see some sample code of yours, if it doesn't violate some restrictions ofcourse.

Here you can wait for a specific VME interrupt-level, and
it returns the vector number. So you can have several applications
connect to the same VME driver, but all on different levels.
 
So, if I understand you correctly, you altered the Motorola driver in order for it to be able to communicate with user spae programms through Xenomai. Which version of Xenomai ws that? I tried to test Xemonai 2.0 on my setup but it iterfred somehow with SSH configuration and thats why i dropped it.
 
Many thanks,
Konstantin

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