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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>
This commit is contained in:
Alan Stern 2011-03-25 11:46:27 -04:00 committed by Greg Kroah-Hartman
parent edf847decc
commit ee81b3e086
2 changed files with 23 additions and 84 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
drivers/usb/gadget/f_mass_storage.c
View File

@ -1569,37 +1569,6 @@ static int wedge_bulk_in_endpoint(struct fsg_dev *fsg)
return rc;
}
static int pad_with_zeros(struct fsg_dev *fsg)
{
struct fsg_buffhd *bh = fsg->common->next_buffhd_to_fill;
u32 nkeep = bh->inreq->length;
u32 nsend;
int rc;
bh->state = BUF_STATE_EMPTY; /* For the first iteration */
fsg->common->usb_amount_left = nkeep + fsg->common->residue;
while (fsg->common->usb_amount_left > 0) {
/* Wait for the next buffer to be free */
while (bh->state != BUF_STATE_EMPTY) {
rc = sleep_thread(fsg->common);
if (rc)
return rc;
}
nsend = min(fsg->common->usb_amount_left, FSG_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->common->next_buffhd_to_fill = bh->next;
fsg->common->usb_amount_left -= nsend;
nkeep = 0;
}
return 0;
}
static int throw_away_data(struct fsg_common *common)
{
struct fsg_buffhd *bh;
@ -1686,6 +1655,10 @@ static int finish_reply(struct fsg_common *common)
if (common->data_size == 0) {
/* Nothing to send */
/* Don't know what to do if common->fsg is NULL */
} else if (!fsg_is_set(common)) {
rc = -EIO;
/* If there's no residue, simply send the last buffer */
} else if (common->residue == 0) {
bh->inreq->zero = 0;
@ -1694,24 +1667,19 @@ static int finish_reply(struct fsg_common *common)
common->next_buffhd_to_fill = bh->next;
/*
* 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 (common->can_stall) {
} else {
bh->inreq->zero = 1;
if (!start_in_transfer(common, bh))
/* Don't know what to do if
* common->fsg is NULL */
rc = -EIO;
common->next_buffhd_to_fill = bh->next;
if (common->fsg)
if (common->can_stall)
rc = halt_bulk_in_endpoint(common->fsg);
} else if (fsg_is_set(common)) {
rc = pad_with_zeros(common->fsg);
} else {
/* Don't know what to do if common->fsg is NULL */
rc = -EIO;
}
break;

53
drivers/usb/gadget/file_storage.c
View File

@ -1932,37 +1932,6 @@ static int wedge_bulk_in_endpoint(struct fsg_dev *fsg)
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 @@ static int finish_reply(struct fsg_dev *fsg)
}
}
/* 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;