From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id ADA72DDFCA for ; Wed, 22 Apr 2009 01:23:47 +1000 (EST) Message-Id: <0C054AA3-9900-4DF0-BD38-6E82EFC327A6@kernel.crashing.org> From: Becky Bruce To: Kumar Gala In-Reply-To: Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Mime-Version: 1.0 (Apple Message framework v930.3) Subject: Re: [PATCH 1/5] powerpc: Use sg->dma_length in sg_dma_len() macro on 32-bit Date: Tue, 21 Apr 2009 10:23:39 -0500 References: <1240244810-32193-1-git-send-email-beckyb@kernel.crashing.org> <1240244810-32193-2-git-send-email-beckyb@kernel.crashing.org> <1240244810-32193-3-git-send-email-beckyb@kernel.crashing.org> <1240244810-32193-4-git-send-email-beckyb@kernel.crashing.org> Cc: fujita.tomonori@lab.ntt.co.jp, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Apr 20, 2009, at 3:06 PM, Kumar Gala wrote: > > On Apr 20, 2009, at 11:26 AM, Becky Bruce wrote: > >> Currently, the 32-bit code uses sg->length instead of sg->dma_lentgh >> to report sg_dma_len. However, since the default dma code for 32-bit >> (the dma_direct case) sets dma_length and length to the same thing, >> we should be able to use dma_length there as well. This gets rid of >> some 32-vs-64-bit ifdefs, and is needed by the swiotlb code which >> actually distinguishes between dma_length and length. >> >> Signed-off-by: Becky Bruce >> --- >> arch/powerpc/include/asm/scatterlist.h | 6 +----- >> 1 files changed, 1 insertions(+), 5 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/scatterlist.h b/arch/powerpc/ >> include/asm/scatterlist.h >> index fcf7d55..912bf59 100644 >> --- a/arch/powerpc/include/asm/scatterlist.h >> +++ b/arch/powerpc/include/asm/scatterlist.h >> @@ -21,7 +21,7 @@ struct scatterlist { >> unsigned int offset; >> unsigned int length; > > can we get rid of length? No - they're both used by the iotlb code and are conceptually different. "dma_length" can get set to less than "length" to indicate that something went wrong with a dma request - the iotlb code sets it to 0 if we can't allocate a bounce buffer, for example. It probably has other uses as well - this is just the one I'm familiar with. In most cases they are equal. Cheers, B