On Wed, 25 Jul 2012, Rajaram REGUPATHY wrote:
> The short_not_ok field is used by class drivers to indicate udc whether short
> packet is expected during a particular transfer.
> In case of mass storage, during command and status phase this field is set as
> false and set to true during data phase.
> musb driver uses this field to decide whether to program DMA for mode1.
> This code is essential for musb driver to program DMA.
>
> Signed-off-by: Balakumar Rajendran <[email protected]>
> Signed-off-by: Rajaram R <[email protected]>
> ---
> drivers/usb/gadget/f_mass_storage.c | 9 +++++++++
> 1 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/gadget/f_mass_storage.c
> b/drivers/usb/gadget/f_mass_storage.c
> index f67b453..db8bf4a 100644
> --- a/drivers/usb/gadget/f_mass_storage.c
> +++ b/drivers/usb/gadget/f_mass_storage.c
> @@ -878,6 +878,7 @@ static int do_write(struct fsg_common *common)
> unsigned int amount;
> ssize_t nwritten;
> int rc;
> + struct usb_gadget *gadget = common->cdev->gadget;
>
> if (curlun->ro) {
> curlun->sense_data = SS_WRITE_PROTECTED; @@ -960,6 +961,8 @@
> static int do_write(struct fsg_common *common)
> * the bulk-out maxpacket size.
> */
> set_bulk_out_req_length(common, bh, amount);
> + if (!gadget_is_superspeed(gadget))
> + bh->outreq->short_not_ok = 1;
This new code is added everywhere set_bulk_out_req_length() is called.
You might as well move it into that function; set short_not_ok whenever
the gadget isn't running at SuperSpeed and the requested length is >=
the block size.
> if (!start_out_transfer(common, bh))
> /* Dunno what to do if common->fsg is NULL */
> return -EIO;
The patch is wrong. Later on in the function we have:
/* Did something go wrong with the transfer? */
if (bh->outreq->status != 0) {
curlun->sense_data = SS_COMMUNICATION_FAILURE;
curlun->sense_data_info =
file_offset >> curlun->blkbits;
curlun->info_valid = 1;
break;
}
We don't want the "if" statement to succeed when the status is nonzero
because a short packet was received.
Alan Stern
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