From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from az33egw01.freescale.net (az33egw01.freescale.net [192.88.158.102]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "az33egw01.freescale.net", Issuer "Thawte Premium Server CA" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 9323FDDFFB for ; Wed, 24 Oct 2007 04:49:25 +1000 (EST) Message-ID: <471E423F.40304@freescale.com> Date: Tue, 23 Oct 2007 13:49:35 -0500 From: Scott Wood MIME-Version: 1.0 To: raul.moreno@telvent.abengoa.com Subject: Re: DMA problem - mpc8xx References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Cc: linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , raul.moreno@telvent.abengoa.com wrote: > Hi everybody, > > I am having problems with the serial cpm driver in a mpc866. But I've found > out that my problem comes from the DMA and not really from the driver. The > Rx and Tx buffers use the DMA and then the sytem hangs. However, if I set > these buffers to internal ram memory (DPRAM), it works. The DMA address is > configured with a kernel parameter in advance setup: > CONFIG_CONSISTENT_START (and the size in CONFIG_CONSISTENT_SIZE), but I > don't know what they are exactly and I could not find a right documentation > about it. > I saw a pair of mailing list where some guys set the > CONFIG_CONSISTENT_START to 0xff100000, but my driver continues failing (and > an error about dma-mapping appears in the boot). What kernel version? arch/ppc or arch/powerpc? What is the error about dma-mapping that you get? What does your memory map look like (in particular, is there anything that might be getting mapped in conflict with the consistent area at 0xff100000)? -Scott