From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH] libata: increase 128 KB / cmd limit for ATAPI tape drives Date: Sat, 03 Nov 2007 08:48:42 -0400 Message-ID: <472C6E2A.8020809@pobox.com> References: <47275163.9020809@cybernetics.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:35171 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753715AbXKCMsn (ORCPT ); Sat, 3 Nov 2007 08:48:43 -0400 In-Reply-To: <47275163.9020809@cybernetics.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tony Battersby Cc: linux-ide@vger.kernel.org Tony Battersby wrote: > Commands sent to ATAPI tape drives via the SCSI generic (sg) driver are > limited in the amount of data that they can transfer by the max_sectors > value. The max_sectors value is currently calculated according to the > command set for disk drives, which doesn't apply to tape drives. The > default max_sectors value of 256 limits ATAPI tape drive commands to > 128 KB. This patch against 2.6.24-rc1 increases the max_sectors value > for tape drives to 65535, which permits tape drive commands to transfer > just under 32 MB. > > Tested with a SuperMicro PDSME motherboard, AHCI, and a Sony SDX-570V > SATA tape drive. > > Note that some of the chipset drivers also set their own max_sectors > value, which may override the value set in libata-core. I don't have > any of these chipsets to test, so I didn't go messing with them. Also, > ATAPI devices other than tape drives may benefit from similar changes, > but I have only tape drives and disk drives to test. > > Signed-off-by: Tony Battersby applied