From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: Impact of no_lba48{_dma} = 1 ? Date: Wed, 07 Feb 2007 16:49:44 +0300 Message-ID: <45C9D8F8.2000303@ru.mvista.com> References: <45C9A23E.3030201@imc-berlin.de> <20070207115826.2e3609e3@localhost.localdomain> <45C9D34E.1060007@imc-berlin.de> <20070207135309.66942d25@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from h155.mvista.com ([63.81.120.155]:34080 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1161304AbXBGNt5 (ORCPT ); Wed, 7 Feb 2007 08:49:57 -0500 In-Reply-To: <20070207135309.66942d25@localhost.localdomain> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cc: Steven Scholz , linux-ide@vger.kernel.org Hello. Alan wrote: >>>Only relevant for DMA really >>So rqsize is only needed for DMA accesses? Not really, it affects both PIO and DMA. > PIO transfers are sector at a time, or multi-sector up to a usual limit > of about 16 sectors. You're clearly mixing 2 things here. PIO transfers are 1 sectors _per interrupt_ or N (usually 16) sectors in the multiple mode. The ANSI specified transfer limit is 256 for LBA28 (which fails on some drives), and 65536 with LBA48 _per command_. MBR, Sergei