From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761099AbZFPRtM (ORCPT ); Tue, 16 Jun 2009 13:49:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754258AbZFPRs6 (ORCPT ); Tue, 16 Jun 2009 13:48:58 -0400 Received: from az33egw02.freescale.net ([192.88.158.103]:40220 "EHLO az33egw02.freescale.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751021AbZFPRs5 (ORCPT ); Tue, 16 Jun 2009 13:48:57 -0400 Message-ID: <4A37DB0F.7060801@freescale.com> Date: Tue, 16 Jun 2009 12:49:03 -0500 From: Scott Wood User-Agent: Mozilla-Thunderbird 2.0.0.19 (X11/20090103) MIME-Version: 1.0 To: Arnd Bergmann CC: linuxppc-dev@lists.ozlabs.org, Chris Pringle , linux-kernel@vger.kernel.org Subject: Re: PowerPC PCI DMA issues (prefetch/coherency?) References: <4A37A503.3030209@oxtel.com> <4A37CF02.5080906@oxtel.com> <4A37D073.6020802@freescale.com> <200906161943.38764.arnd@arndb.de> In-Reply-To: <200906161943.38764.arnd@arndb.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAWE= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arnd Bergmann wrote: > On Tuesday 16 June 2009, Scott Wood wrote: >> Chris Pringle wrote: >>> Ah right - that would explain what we're seeing then... Doh. Thought I >>> might have been onto something then. Is there any way to force a cache >>> flush? That'd at least prove it was a caching issue if it resolved the >>> problem. >> You could enable CONFIG_NOT_COHERENT_CACHE. > > If the whole system is noncoherent, that is the right solution. I meant it more as a test than a permanent solution... > If the > device is the only one, you can also use dma_alloc_noncoherent() and > flush explicitly with dma_cache_sync(). I don't see how that would help -- aren't those also controlled by CONFIG_NOT_COHERENT_CACHE? -Scott From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from az33egw02.freescale.net (az33egw02.freescale.net [192.88.158.103]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "az33egw02.freescale.net", Issuer "Thawte Premium Server CA" (verified OK)) by bilbo.ozlabs.org (Postfix) with ESMTPS id 91976B71A8 for ; Wed, 17 Jun 2009 03:48:55 +1000 (EST) Message-ID: <4A37DB0F.7060801@freescale.com> Date: Tue, 16 Jun 2009 12:49:03 -0500 From: Scott Wood MIME-Version: 1.0 To: Arnd Bergmann Subject: Re: PowerPC PCI DMA issues (prefetch/coherency?) References: <4A37A503.3030209@oxtel.com> <4A37CF02.5080906@oxtel.com> <4A37D073.6020802@freescale.com> <200906161943.38764.arnd@arndb.de> In-Reply-To: <200906161943.38764.arnd@arndb.de> Content-Type: text/plain; charset=UTF-8; format=flowed Cc: Chris Pringle , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Arnd Bergmann wrote: > On Tuesday 16 June 2009, Scott Wood wrote: >> Chris Pringle wrote: >>> Ah right - that would explain what we're seeing then... Doh. Thought I >>> might have been onto something then. Is there any way to force a cache >>> flush? That'd at least prove it was a caching issue if it resolved the >>> problem. >> You could enable CONFIG_NOT_COHERENT_CACHE. > > If the whole system is noncoherent, that is the right solution. I meant it more as a test than a permanent solution... > If the > device is the only one, you can also use dma_alloc_noncoherent() and > flush explicitly with dma_cache_sync(). I don't see how that would help -- aren't those also controlled by CONFIG_NOT_COHERENT_CACHE? -Scott