Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753270Ab1CUOU4 (ORCPT ); Mon, 21 Mar 2011 10:20:56 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:55897 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752067Ab1CUOUy (ORCPT ); Mon, 21 Mar 2011 10:20:54 -0400 Date: Mon, 21 Mar 2011 10:20:52 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Roger Quadros cc: gregkh@suse.de, , , Subject: Re: [PATCH v2 1/3] usb: gadget: storage: Add fsg_get_toc helper In-Reply-To: <1300705159-24386-2-git-send-email-roger.quadros@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: 3072 Lines: 83 On Mon, 21 Mar 2011, Roger Quadros wrote: > From: Roger Quadros > > fsg_get_toc can be used by both storage gadgets to build a CD-ROM > Table of Contents which can be used as data for READ_TOC command. > Currently fsg_get_toc supports two TOC formats, i.e. > format 0: Formatted TOC and format 2: Raw TOC. > > Raw TOC is required for CD-ROM emulation to work with Mac OS-X. > > Signed-off-by: Roger Quadros > --- > drivers/usb/gadget/storage_common.c | 68 +++++++++++++++++++++++++++++++++++ > 1 files changed, 68 insertions(+), 0 deletions(-) > > diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c > index b015561..d47f148 100644 > --- a/drivers/usb/gadget/storage_common.c > +++ b/drivers/usb/gadget/storage_common.c > @@ -655,6 +655,74 @@ static void store_cdrom_address(u8 *dest, int msf, u32 addr) > } > } > > +/** > + * fsg_get_toc() - Builds a TOC with required format @format. > + * @curlun: The LUN for which the TOC has to be built > + * @msf: Min Sec Frame format or LBA format for address > + * @format: TOC format code > + * @buf: The buffer into which the TOC is built > + * > + * Builds a Table of Content which can be used as data for READ_TOC command. > + * The TOC simulates a single session, single track CD-ROM mode 1 disc. > + * > + * Returns number of bytes written to @buf, -EINVAL if format not supported. > + */ > +static int fsg_get_toc(struct fsg_lun *curlun, int msf, int format, u8 *buf) > +{ > + int i, len; > + switch (format) { > + case 0: > + /* Formatted TOC */ > + len = 4 + 2*8; /* 4 byte header + 2 descriptors */ > + memset(buf, 0, len); > + len -= 2; /* TOC Length excludes length field */ > + buf[1] = len; /* TOC data length */ These two lines are wrong. You should do: buf[1] = len - 2; /* TOC data length excludes header */ The way it is now, the function ends up returning 18 instead of 20, causing the wrong amount of data to be transmitted. > + buf[2] = 1; /* First track number */ > + buf[3] = 1; /* Last track number */ > + buf[5] = 0x16; /* Data track, copying allowed */ > + buf[6] = 0x01; /* Only track is number 1 */ > + store_cdrom_address(&buf[8], msf, 0); > + > + buf[13] = 0x16; /* Lead-out track is data */ > + buf[14] = 0xAA; /* Lead-out track number */ > + store_cdrom_address(&buf[16], msf, curlun->num_sectors); > + return len; > + break; > + > + case 2: > + /* Raw TOC */ > + len = 4 + 3*11; /* 4 byte header + 3 descriptors */ > + memset(buf, 0, len); /* Header + A0, A1 & A2 descriptors */ > + len -= 2; /* TOC Length excludes length field */ > + buf[1] = len; /* TOC data length */ Same thing here. I'm surprised it worked during testing. Did you really check to see that the correct data was being sent? 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/