From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 01 Oct 2007 21:33:39 +0100 (BST) Received: from n7.bullet.mud.yahoo.com ([216.252.100.58]:39785 "HELO n7.bullet.mud.yahoo.com") by ftp.linux-mips.org with SMTP id S20021983AbXJAUda (ORCPT ); Mon, 1 Oct 2007 21:33:30 +0100 Received: from [68.142.194.244] by n7.bullet.mud.yahoo.com with NNFMP; 01 Oct 2007 20:33:23 -0000 Received: from [209.191.119.153] by t2.bullet.mud.yahoo.com with NNFMP; 01 Oct 2007 20:33:23 -0000 Received: from [127.0.0.1] by omp100.mail.mud.yahoo.com with NNFMP; 01 Oct 2007 20:08:15 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 842743.27969.bm@omp100.mail.mud.yahoo.com Received: (qmail 48437 invoked by uid 60001); 1 Oct 2007 12:10:59 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.in; h=X-YMail-OSG:Received:Date:From:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID; b=JFI93gjpzOHlXrYO0qKiBrK2exRN0OUN5mgune/EHusbnjKGeS2+sEvK9Tn0eMPo1KvwogV0XtXLOa8+OtabFNg6kjPzE6/DBzH/XSkEeYxjkQACFOyyLaFoaEyO6w9yo/TykbbTHV1rzLQEClIKfNh61EHkhDIwEPLSFCcJVpE=; X-YMail-OSG: 2Ig8bTcVM1nO9td6myIxXt9.FpWVrwmpuK_jDH2VK_Z13tLNAiMLCRCEa2vgXw9UmqssKi2L8wJOBb2MetWIWOxLM0VENOwBoLeO8r.4zPTX.bC6fUVqfh4iVQ-- Received: from [199.239.167.162] by web8403.mail.in.yahoo.com via HTTP; Mon, 01 Oct 2007 13:10:59 BST Date: Mon, 1 Oct 2007 13:10:59 +0100 (BST) From: veerasena reddy Subject: Re: linux cache routines for Write-back cache policy on MIPS24KE To: Ralf Baechle Cc: linux-mips , "linux-kernel.org" In-Reply-To: <20071001105954.GB23647@linux-mips.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Message-ID: <535696.48077.qm@web8403.mail.in.yahoo.com> Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 16780 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: veerasena_b@yahoo.co.in Precedence: bulk X-list: linux-mips Hi Ralf, Thanks for the reply. Is there any problem if we use the below API's in linxu-2.6.18 - dma_cache_wback_inv() - dma_cache_wback() - dma_cache_inv() functionality wise, especially in r4k.c i dont see any difference between the implementation of these APIs. Can we apply the 2.6.24 patch to kill these APIs on 2.6.18 kernel? In this case what APIs i can use for writeback, invalidation or both? I couldn't find any info. related to the above API in DMA-API.txt. Could you please give some pointers on the usage/working of these APIs. Regards, Veerasena. --- Ralf Baechle wrote: > On Mon, Oct 01, 2007 at 10:04:32AM +0100, veerasena > reddy wrote: > > > I have ported Linux-2.6.18 kernel on MIPS24KE > > processor. I am using write back cache policy. > > > > Could you please guide me under what cases the > below > > cache API's are being used: > > - dma_cache_wback_inv() : Could you explain what > > exactly this function does > > - dma_cache_wback() : This function write back the > > cache data to memory > > - dma_cache_inv : This function invalidate the > cache > > tags. so subsequent access will fetch from memory. > > > > Once I looked the above function definitions in > > linux-2.6.18/arch/mips/mm/c-r4k.c. > > All these function's implemetation are same except > > bc_wbak_inv() is called in both > dma_cache_wback-inv() > > and dma_cache_wback(), where as bc_inv() is called > in > > case of dma_cache_inv. > > > > Also, bc_inv()/bc_wbak_inv are define as null > > implementation for R4000. > > That means all three functions are doing same > > functionality in case of R4000. > > > > What are the difference between these three > functions. > > Under what cases these functions are used. > > An internal only interface to be used with I/O cache > coherency. > > > Please guide me if you have any links which will > > explain these API's. > > Easy answer, don't use them, for 2.6.24 I've queued > a patch to kill this > API. Documentation/DMA-API.txt documents how to > properly deal with I/O > coherency in Linux. > > Ralf > Save all your chat conversations. Find them online at http://in.messenger.yahoo.com/webmessengerpromo.php