From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: Issues with commit 34b48db6 ("block: remove artifical max_hw_sectors cap") Date: Tue, 30 Dec 2014 12:28:09 +0100 Message-ID: <20141230112809.GA1360@lst.de> References: <20141227151319.GA18607@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from verein.lst.de ([213.95.11.211]:47360 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751979AbaL3L2N (ORCPT ); Tue, 30 Dec 2014 06:28:13 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Stern Cc: "Kenneth R. Crudup" , linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net On Sun, Dec 28, 2014 at 10:10:01PM -0500, Alan Stern wrote: > (Is this a USB device? Presumably you wouldn't have CC'ed the > linux-usb and usb-storage mailing lists if it wasn't...) It's a usb attached device. From the inquity information and the product name it looks like a SATA device attached via a usb bridge. > The only limits usb-storage imposes on max_sectors are those needed to > work around bugs in the devices' USB bridges. (Okay, there's also > something for tape drive devices, but it probably doesn't belong in > usb-storage -- it should be handled by the SCSI tape driver.) > > If the ATA layer needs to set a limit on max_sectors, why doesn't it > simply go ahead and do so? Because the ATA layer doesn't control the device, the bridge does. And it seems like it doesn't communicate the maximum transfer size properly.