From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH #upstream-fixes] sata_mv: don't issue two DMA commands concurrently Date: Tue, 26 Aug 2008 09:04:31 +0200 Message-ID: <48B3AAFF.5010704@gmail.com> References: <489C19CE.6030708@ngs.ru> <489C4B6E.9070306@rtr.ca> <489C4F29.6020007@rtr.ca> <489C54D1.5080901@rtr.ca> <48A29E14.3090908@gmail.com> <48A2BBDC.2090201@ngs.ru> <48A2BC5D.5060801@gmail.com> <48A2C35C.7020400@ngs.ru> <48A2C460.6040504@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ti-out-0910.google.com ([209.85.142.190]:51122 "EHLO ti-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750954AbYHZHFk (ORCPT ); Tue, 26 Aug 2008 03:05:40 -0400 Received: by ti-out-0910.google.com with SMTP id b6so1196681tic.23 for ; Tue, 26 Aug 2008 00:05:38 -0700 (PDT) In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Gwendal Grignou Cc: Artem Bokhan , Jeff Garzik , Mark Lord , linux-ide@vger.kernel.org Gwendal Grignou wrote: > What happen if there is a SATA port multiplier behing the marvell > controller and NCQ is disabled? > > I have the impression that with this patch we are able to only send > one DMA command at a time to all the drives behind the PM, which has > an impact on performance. Yeah, right. :-( The simplest way to implement this would be just calling ata_std_qc_defer() which computes per-link restrictions after ruling out all non-standard restrictions. I wasn't really sure how EDMA/NCQ_EN flags are supposed to work so just sticked to the original condition tests. Mark, can you please help us out here? :-) Thanks. -- tejun