On Mon, 10 Dec 2012, Michal Nazarewicz wrote:
> On Mon, Dec 10 2012, Golmer Palmer <[email protected]> wrote:
> > This message is for request to support CD-ROM boot support in the USB
> > Gadget
> > driver.
> >
> > Specifically, I ask for improve "g_mass_storage" driver with:
> >
> > * 2048 byte/sector support in CD mode.
>
> Unless I'm missing something, g_mass_storage is using 2048 sector size
> for CD-ROMs. See initialisation of blksize in fsg_lun_open() in
> storage_common.c.
>
> > * workaround for READ TOC command with incorrect length.
>
> Does the following help:
>
> ----------------- >8 ---------------------------------------------------
> drivers/usb/gadget/f_mass_storage.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/usb/gadget/f_mass_storage.c
> b/drivers/usb/gadget/f_mass_storage.c
> index 5d027b3..850d779 100644
> --- a/drivers/usb/gadget/f_mass_storage.c
> +++ b/drivers/usb/gadget/f_mass_storage.c
> @@ -1823,7 +1823,12 @@ static int check_command(struct fsg_common *common,
> int cmnd_size,
>
> /* Check that only command bytes listed in the mask are non-zero */
> common->cmnd[1] &= 0x1f; /* Mask away the LUN */
> - for (i = 1; i < cmnd_size; ++i) {
> + /*
> + * Some BIOSes put some non-zero values in READ_TOC requests in the
> + * last two bytes -- Andreas Kemnade. So let's exclude those.
> + */
> + i = common->cmnd[0] == READ_TOC ? cmnd_size - 2 : cmnd_size;
> + while (--i >= 1) {
> if (common->cmnd[i] && !(mask & (1 << i))) {
> if (curlun)
> curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
> ----------------- >8 ---------------------------------------------------
By the way, that's not the right way to do this. Here's the proper
patch.
Alan Stern
Index: usb-3.7/drivers/usb/gadget/f_mass_storage.c
===================================================================
--- usb-3.7.orig/drivers/usb/gadget/f_mass_storage.c
+++ usb-3.7/drivers/usb/gadget/f_mass_storage.c
@@ -1995,8 +1995,13 @@ static int do_scsi_command(struct fsg_co
goto unknown_cmnd;
common->data_size_from_cmnd =
get_unaligned_be16(&common->cmnd[7]);
+ /*
+ * According to Andreas Kemnade, some BIOSes incorrectly
+ * put nonzero values in the "control" byte of READ TOC
+ * commands. So let's accept them.
+ */
reply = check_command(common, 10, DATA_DIR_TO_HOST,
- (7<<6) | (1<<1), 1,
+ (1<<9) | (7<<6) | (1<<1), 1,
"READ TOC");
if (reply == 0)
reply = do_read_toc(common, bh);
--
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