[PATCH 3.10 27/54] usb: xhci: Add support for URB_ZERO_PACKET to bulk/sg transfers

Greg Kroah-Hartman
2015-10-18T02:52:07Z

From: Reyad Attiyat <reyad.attiyat@gmail.com>

commit 4758dcd19a7d9ba9610b38fecb93f65f56f86346 upstream.

This commit checks for the URB_ZERO_PACKET flag and creates an extra
zero-length td if the urb transfer length is a multiple of the endpoint's
max packet length.

Signed-off-by: Reyad Attiyat <reyad.attiyat@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Cc: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/host/xhci-ring.c | 66 +++++++++++++++++++++++++++++++++----------
drivers/usb/host/xhci.c | 5 +++
2 files changed, 57 insertions(+), 14 deletions(-)

--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -3167,9 +3167,11 @@ static int queue_bulk_sg_tx(struct xhci_
struct xhci_td *td;
struct scatterlist *sg;
int num_sgs;
- int trb_buff_len, this_sg_len, running_total;
+ int trb_buff_len, this_sg_len, running_total, ret;
unsigned int total_packet_count;
+ bool zero_length_needed;
bool first_trb;
+ int last_trb_num;
u64 addr;
bool more_trbs_coming;

@@ -3185,13 +3187,27 @@ static int queue_bulk_sg_tx(struct xhci_
total_packet_count = DIV_ROUND_UP(urb->transfer_buffer_length,
usb_endpoint_maxp(&urb->ep->desc));

- trb_buff_len = prepare_transfer(xhci, xhci->devs[slot_id],
+ ret = prepare_transfer(xhci, xhci->devs[slot_id],
ep_index, urb->stream_id,
num_trbs, urb, 0, mem_flags);
- if (trb_buff_len < 0)
- return trb_buff_len;
+ if (ret < 0)
+ return ret;

urb_priv = urb->hcpriv;
+
+ /* Deal with URB_ZERO_PACKET - need one more td/trb */
+ zero_length_needed = urb->transfer_flags & URB_ZERO_PACKET &&
+ urb_priv->length == 2;
+ if (zero_length_needed) {
+ num_trbs++;
+ xhci_dbg(xhci, "Creating zero length td.\n");
+ ret = prepare_transfer(xhci, xhci->devs[slot_id],
+ ep_index, urb->stream_id,
+ 1, urb, 1, mem_flags);
+ if (ret < 0)
+ return ret;
+ }
+
td = urb_priv->td[0];

/*
@@ -3221,6 +3237,7 @@ static int queue_bulk_sg_tx(struct xhci_
trb_buff_len = urb->transfer_buffer_length;

first_trb = true;
+ last_trb_num = zero_length_needed ? 2 : 1;
/* Queue the first TRB, even if it's zero-length */
do {
u32 field = 0;
@@ -3238,12 +3255,15 @@ static int queue_bulk_sg_tx(struct xhci_
/* Chain all the TRBs together; clear the chain bit in the last
* TRB to indicate it's the last TRB in the chain.
*/
- if (num_trbs > 1) {
+ if (num_trbs > last_trb_num) {
field |= TRB_CHAIN;
- } else {
- /* FIXME - add check for ZERO_PACKET flag before this */
+ } else if (num_trbs == last_trb_num) {
td->last_trb = ep_ring->enqueue;
field |= TRB_IOC;
+ } else if (zero_length_needed && num_trbs == 1) {
+ trb_buff_len = 0;
+ urb_priv->td[1]->last_trb = ep_ring->enqueue;
+ field |= TRB_IOC;
}

/* Only set interrupt on short packet for IN endpoints */
@@ -3305,7 +3325,7 @@ static int queue_bulk_sg_tx(struct xhci_
if (running_total + trb_buff_len > urb->transfer_buffer_length)
trb_buff_len =
urb->transfer_buffer_length - running_total;
- } while (running_total < urb->transfer_buffer_length);
+ } while (num_trbs > 0);

check_trb_math(urb, num_trbs, running_total);
giveback_first_trb(xhci, slot_id, ep_index, urb->stream_id,
@@ -3323,7 +3343,9 @@ int xhci_queue_bulk_tx(struct xhci_hcd *
int num_trbs;
struct xhci_generic_trb *start_trb;
bool first_trb;
+ int last_trb_num;
bool more_trbs_coming;
+ bool zero_length_needed;
int start_cycle;
u32 field, length_field;

@@ -3354,7 +3376,6 @@ int xhci_queue_bulk_tx(struct xhci_hcd *
num_trbs++;
running_total += TRB_MAX_BUFF_SIZE;
}
- /* FIXME: this doesn't deal with URB_ZERO_PACKET - need one more */

ret = prepare_transfer(xhci, xhci->devs[slot_id],
ep_index, urb->stream_id,
@@ -3363,6 +3384,20 @@ int xhci_queue_bulk_tx(struct xhci_hcd *
return ret;

urb_priv = urb->hcpriv;
+
+ /* Deal with URB_ZERO_PACKET - need one more td/trb */
+ zero_length_needed = urb->transfer_flags & URB_ZERO_PACKET &&
+ urb_priv->length == 2;
+ if (zero_length_needed) {
+ num_trbs++;
+ xhci_dbg(xhci, "Creating zero length td.\n");
+ ret = prepare_transfer(xhci, xhci->devs[slot_id],
+ ep_index, urb->stream_id,
+ 1, urb, 1, mem_flags);
+ if (ret < 0)
+ return ret;
+ }
+
td = urb_priv->td[0];

/*
@@ -3384,7 +3419,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *
trb_buff_len = urb->transfer_buffer_length;

first_trb = true;
-
+ last_trb_num = zero_length_needed ? 2 : 1;
/* Queue the first TRB, even if it's zero-length */
do {
u32 remainder = 0;
@@ -3401,12 +3436,15 @@ int xhci_queue_bulk_tx(struct xhci_hcd *
/* Chain all the TRBs together; clear the chain bit in the last
* TRB to indicate it's the last TRB in the chain.
*/
- if (num_trbs > 1) {
+ if (num_trbs > last_trb_num) {
field |= TRB_CHAIN;
- } else {
- /* FIXME - add check for ZERO_PACKET flag before this */
+ } else if (num_trbs == last_trb_num) {
td->last_trb = ep_ring->enqueue;
field |= TRB_IOC;
+ } else if (zero_length_needed && num_trbs == 1) {
+ trb_buff_len = 0;
+ urb_priv->td[1]->last_trb = ep_ring->enqueue;
+ field |= TRB_IOC;
}

/* Only set interrupt on short packet for IN endpoints */
@@ -3444,7 +3482,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *
trb_buff_len = urb->transfer_buffer_length - running_total;
if (trb_buff_len > TRB_MAX_BUFF_SIZE)
trb_buff_len = TRB_MAX_BUFF_SIZE;
- } while (running_total < urb->transfer_buffer_length);
+ } while (num_trbs > 0);

check_trb_math(urb, num_trbs, running_total);
giveback_first_trb(xhci, slot_id, ep_index, urb->stream_id,
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1300,6 +1300,11 @@ int xhci_urb_enqueue(struct usb_hcd *hcd

if (usb_endpoint_xfer_isoc(&urb->ep->desc))
size = urb->number_of_packets;
+ else if (usb_endpoint_is_bulk_out(&urb->ep->desc) &&
+ urb->transfer_buffer_length > 0 &&
+ urb->transfer_flags & URB_ZERO_PACKET &&
+ !(urb->transfer_buffer_length % usb_endpoint_maxp(&urb->ep->desc)))
+ size = 2;
else
size = 1;