From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754997AbcCNHV3 (ORCPT ); Mon, 14 Mar 2016 03:21:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:54919 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754841AbcCNHVM (ORCPT ); Mon, 14 Mar 2016 03:21:12 -0400 Subject: Re: [PATCH 01/22] g_ncr5380: Remove CONFIG_SCSI_GENERIC_NCR53C400 To: Finn Thain , "James E.J. Bottomley" , "Martin K. Petersen" , Michael Schmitz , linux-m68k@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <20160314042700.596192247@telegraphics.com.au> <20160314042700.855969695@telegraphics.com.au> Cc: Ondrej Zary , Sam Creasey From: Hannes Reinecke Message-ID: <56E66663.2030704@suse.de> Date: Mon, 14 Mar 2016 08:21:07 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160314042700.855969695@telegraphics.com.au> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/14/2016 05:27 AM, Finn Thain wrote: > This change brings a number of improvements: fewer macros, better test > coverage, simpler code and sane Kconfig options. The downside is a small > chance of incompatibility (which seems unavoidable). > > CONFIG_SCSI_GENERIC_NCR53C400 exists to enable or inhibit pseudo DMA > transfers when the driver is used with 53C400-compatible cards. Thanks to > Ondrej Zary's patches, PDMA now works which means it can be enabled > unconditionally. > > Due to bad design, CONFIG_SCSI_GENERIC_NCR53C400 ties together unrelated > functionality as it sets both PSEUDO_DMA and BIOSPARAM macros. This patch > effectively enables PSEUDO_DMA and disables BIOSPARAM. > > The defconfigs and the Kconfig default leave CONFIG_SCSI_GENERIC_NCR53C400 > undefined. Red Hat 9 and CentOS 2.1 were the same. This leaves both > PSEUDO_DMA and BIOSPARAM disabled. The effect of this patch should be > better performance from enabling PSEUDO_DMA. > > On the other hand, Debian 4 and SLES 10 had CONFIG_SCSI_GENERIC_NCR53C400 > enabled, so both PSEUDO_DMA and BIOSPARAM were enabled. This patch might > affect configurations like this by disabling BIOSPARAM. My best guess is > that this could be a problem only in the vanishingly rare case that > 1) the CHS values stored in the boot device partition table are wrong and > 2) a 5380 card is in use (because PDMA on 53C400 used to be broken). > > Signed-off-by: Finn Thain > > --- > Reviewed-by: Hannes Reinecke And don't worry about SLES10; we won't backport your fixes to _that_. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)