Messages in this thread | | | Date | Mon, 21 Mar 2011 17:29:14 +0200 | From | Roger Quadros <> | Subject | Re: [PATCH v2 1/3] usb: gadget: storage: Add fsg_get_toc helper |
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On 03/21/2011 04:20 PM, ext Alan Stern wrote: > On Mon, 21 Mar 2011, Roger Quadros wrote: > >> From: Roger Quadros<roger.quadros@nokia.com> >> >> 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<roger.quadros@nokia.com> >> --- >> 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.
Yes indeed.
> >> + 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?
I too am surprised. I tried playing a few videos without problems. After you pointed out the problem I ran a checksum on the files and they match!!
But thanks for pointing out, I'll send a new patch.
-- regards, -roger
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