Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754879Ab1CVO0h (ORCPT ); Tue, 22 Mar 2011 10:26:37 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:57611 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752328Ab1CVO0f (ORCPT ); Tue, 22 Mar 2011 10:26:35 -0400 Date: Tue, 22 Mar 2011 10:26:34 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Roger Quadros cc: gregkh@suse.de, , , Subject: Re: [PATCH v2 2/3] usb: gadget: file_storage: Make CD-ROM emulation work with Mac OS-X In-Reply-To: <4D88AF6F.4050508@nokia.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1534 Lines: 43 On Tue, 22 Mar 2011, Roger Quadros wrote: > I have a question here. > > The host can request us to send less or more than the actual TOC size, since it > has no clue how big it is. > e.g. Linux host requests us to send only 12 bytes even though our formatted TOC > length is 20. In this case should we return fsg->data_size_from_cmnd instead of > actual TOC length? No. Always return the actual TOC length. > e.g. Mac requests us to send 65534 bytes but our RAW TOC length is 37. > The file storage driver seems to be zero padding our data response. So we > respond with 65534 bytes, 37 of TOC and remaining zero padded. > > Can we do something like this to avoid unnecessary zero padded transfers? > > ret = fsg_get_toc(curlun, msf, format, buf); > if (ret < 0) { > curlun->sense_data = SS_INVALID_FIELD_IN_CDB; > return -EINVAL; > } else if (ret > fsg->data_size_from_cmnd) { > ret = fsg->data_size_from_cmnd; > } else { > fsg->residue = ret; > } > return ret; Not needed (and not correct). The code at the end of do_scsi_command() already does this: reply = min((u32) reply, fsg->data_size_from_cmnd); ... fsg->residue -= reply; Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/