USB: g_file_storage: don't send padding when stall=n
This patch (as1455) removes the extra padding sent by g_file_storage
and g_mass_storage when the gadget wants to send less data than
requested by the host and isn't allowed to halt the bulk-IN endpoint.
Although the Bulk-Only Transport specification requires the padding to
be present, it isn't truly needed since the transfer will be terminated
by a short packet anyway. Furthermore, many existing devices don't
bother to send any padding.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-By: Michal Nazarewicz <mina86@mina86.com>
CC: Roger Quadros <roger.quadros@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index d04e0e6..aebfb81f 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -1932,37 +1932,6 @@
return rc;
}
-static int pad_with_zeros(struct fsg_dev *fsg)
-{
- struct fsg_buffhd *bh = fsg->next_buffhd_to_fill;
- u32 nkeep = bh->inreq->length;
- u32 nsend;
- int rc;
-
- bh->state = BUF_STATE_EMPTY; // For the first iteration
- fsg->usb_amount_left = nkeep + fsg->residue;
- while (fsg->usb_amount_left > 0) {
-
- /* Wait for the next buffer to be free */
- while (bh->state != BUF_STATE_EMPTY) {
- rc = sleep_thread(fsg);
- if (rc)
- return rc;
- }
-
- nsend = min(fsg->usb_amount_left, (u32) mod_data.buflen);
- memset(bh->buf + nkeep, 0, nsend - nkeep);
- bh->inreq->length = nsend;
- bh->inreq->zero = 0;
- start_transfer(fsg, fsg->bulk_in, bh->inreq,
- &bh->inreq_busy, &bh->state);
- bh = fsg->next_buffhd_to_fill = bh->next;
- fsg->usb_amount_left -= nsend;
- nkeep = 0;
- }
- return 0;
-}
-
static int throw_away_data(struct fsg_dev *fsg)
{
struct fsg_buffhd *bh;
@@ -2066,18 +2035,20 @@
}
}
- /* For Bulk-only, if we're allowed to stall then send the
- * short packet and halt the bulk-in endpoint. If we can't
- * stall, pad out the remaining data with 0's. */
+ /*
+ * For Bulk-only, mark the end of the data with a short
+ * packet. If we are allowed to stall, halt the bulk-in
+ * endpoint. (Note: This violates the Bulk-Only Transport
+ * specification, which requires us to pad the data if we
+ * don't halt the endpoint. Presumably nobody will mind.)
+ */
else {
- if (mod_data.can_stall) {
- bh->inreq->zero = 1;
- start_transfer(fsg, fsg->bulk_in, bh->inreq,
- &bh->inreq_busy, &bh->state);
- fsg->next_buffhd_to_fill = bh->next;
+ bh->inreq->zero = 1;
+ start_transfer(fsg, fsg->bulk_in, bh->inreq,
+ &bh->inreq_busy, &bh->state);
+ fsg->next_buffhd_to_fill = bh->next;
+ if (mod_data.can_stall)
rc = halt_bulk_in_endpoint(fsg);
- } else
- rc = pad_with_zeros(fsg);
}
break;