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Commit ee81b3e0 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
Browse files

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: default avatarAlan Stern <stern@rowland.harvard.edu>
Acked-By: default avatarMichal Nazarewicz <mina86@mina86.com>
CC: Roger Quadros <roger.quadros@nokia.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent edf847de

drivers/usb/gadget/f_mass_storage.c

+11 −43
Original line number Diff line number Diff line
@@ -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;

drivers/usb/gadget/file_storage.c

+12 −41
Original line number Diff line number Diff line
@@ -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;

			if (mod_data.can_stall)

				rc = halt_bulk_in_endpoint(fsg);

			} else

				rc = pad_with_zeros(fsg);

		}

		break;