[PATCH v2 2/3] usb: gadget: NCM: Add transmit multi-frame.

From: Jim Baxter
Date: Mon Jul 07 2014 - 13:33:59 EST

This adds multi-frame support to the NCM NTB's for
the gadget driver. This allows multiple network
packets to be put inside a single USB NTB with a
maximum size of 16kB.

It has a time out of 300ms to ensure that smaller
number of packets still maintain a normal latency.

Also the .fp_index and .next_fp_index have been
changed to .ndp_index and .next_ndp_index to
match the latest CDC-NCM specification and
help with maintenance.

Results transmitting from gadget to host.

Before the change:

TCP_STREAM Throughput (10^6bits/sec): 22.72
UDP_STREAM Throughput (10^6bits/sec): 25.94

Latency:
netperf -H 192.168.1.101 -v2 -l 50 -t TCP_RR -- -r 16384,16384
Trans. RoundTrip Throughput
Rate Latency 10^6bits/s
per sec usec/Tran Outbound

100.83 9918.116 13.215

After the change:

TCP_STREAM Throughput (10^6bits/sec): 124.26
UDP_STREAM Throughput (10^6bits/sec): 227.48

Latency:
netperf -H 192.168.1.101 -v2 -l 50 -t TCP_RR -- -r 16384,16384
Trans. RoundTrip Throughput
Rate Latency 10^6bits/s
per sec usec/Tran Outbound

156.80 6377.730 20.552

Signed-off-by: Jim Baxter <jim_baxter@xxxxxxxxxx>
---
drivers/usb/gadget/f_ncm.c | 335 ++++++++++++++++++++++++++++++++----------
drivers/usb/gadget/u_ether.c | 19 ++-
drivers/usb/gadget/u_ether.h | 2 +
3 files changed, 269 insertions(+), 87 deletions(-)

diff --git a/drivers/usb/gadget/f_ncm.c b/drivers/usb/gadget/f_ncm.c
index d0ebbac..5452fb6 100644
--- a/drivers/usb/gadget/f_ncm.c
+++ b/drivers/usb/gadget/f_ncm.c
@@ -68,6 +68,18 @@ struct f_ncm {
* callback and ethernet open/close
*/
spinlock_t lock;
+
+ struct net_device *netdev;
+
+ /* For multi-frame NDP TX */
+ struct sk_buff *skb_tx_data;
+ struct sk_buff *skb_tx_ndp;
+ u16 ndp_dgram_count;
+ bool timer_force_tx;
+ struct tasklet_struct tx_tasklet;
+ struct hrtimer task_timer;
+
+ bool timer_stopping;
};

static inline struct f_ncm *func_to_ncm(struct usb_function *f)
@@ -92,15 +104,20 @@ static inline unsigned ncm_bitrate(struct usb_gadget *g)
* If the host can group frames, allow it to do that, 16K is selected,
* because it's used by default by the current linux host driver
*/
-#define NTB_DEFAULT_IN_SIZE USB_CDC_NCM_NTB_MIN_IN_SIZE
+#define NTB_DEFAULT_IN_SIZE 16384
#define NTB_OUT_SIZE 16384

-/*
- * skbs of size less than that will not be aligned
- * to NCM's dwNtbInMaxSize to save bus bandwidth
+/* Allocation for storing the NDP, 32 should suffice for a
+ * 16k packet. This allows a maximum of 32 * 507 Byte packets to
+ * be transmitted in a single 16kB skb, though when sending full size
+ * packets this limit will be plenty.
+ * Smaller packets are not likely to be trying to maximize the
+ * throughput and will be mstly sending smaller infrequent frames.
*/
+#define TX_MAX_NUM_DPE 32

-#define MAX_TX_NONFIXED (512 * 3)
+/* Delay for the transmit to wait before sending an unfilled NTB frame. */
+#define TX_TIMEOUT_NSECS 300000

#define FORMATS_SUPPORTED (USB_CDC_NCM_NTB16_SUPPORTED | \
USB_CDC_NCM_NTB32_SUPPORTED)
@@ -355,14 +372,15 @@ struct ndp_parser_opts {
u32 ndp_sign;
unsigned nth_size;
unsigned ndp_size;
+ unsigned dpe_size;
unsigned ndplen_align;
/* sizes in u16 units */
unsigned dgram_item_len; /* index or length */
unsigned block_length;
- unsigned fp_index;
+ unsigned ndp_index;
unsigned reserved1;
unsigned reserved2;
- unsigned next_fp_index;
+ unsigned next_ndp_index;
};

#define INIT_NDP16_OPTS { \
@@ -370,13 +388,14 @@ struct ndp_parser_opts {
.ndp_sign = USB_CDC_NCM_NDP16_NOCRC_SIGN, \
.nth_size = sizeof(struct usb_cdc_ncm_nth16), \
.ndp_size = sizeof(struct usb_cdc_ncm_ndp16), \
+ .dpe_size = sizeof(struct usb_cdc_ncm_dpe16), \
.ndplen_align = 4, \
.dgram_item_len = 1, \
.block_length = 1, \
- .fp_index = 1, \
+ .ndp_index = 1, \
.reserved1 = 0, \
.reserved2 = 0, \
- .next_fp_index = 1, \
+ .next_ndp_index = 1, \
}


@@ -385,13 +404,14 @@ struct ndp_parser_opts {
.ndp_sign = USB_CDC_NCM_NDP32_NOCRC_SIGN, \
.nth_size = sizeof(struct usb_cdc_ncm_nth32), \
.ndp_size = sizeof(struct usb_cdc_ncm_ndp32), \
+ .dpe_size = sizeof(struct usb_cdc_ncm_dpe32), \
.ndplen_align = 8, \
.dgram_item_len = 2, \
.block_length = 2, \
- .fp_index = 2, \
+ .ndp_index = 2, \
.reserved1 = 1, \
.reserved2 = 2, \
- .next_fp_index = 2, \
+ .next_ndp_index = 2, \
}

static const struct ndp_parser_opts ndp16_opts = INIT_NDP16_OPTS;
@@ -803,6 +823,8 @@ static int ncm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)

if (ncm->port.in_ep->driver_data) {
DBG(cdev, "reset ncm\n");
+ ncm->timer_stopping = true;
+ ncm->netdev = NULL;
gether_disconnect(&ncm->port);
ncm_reset_values(ncm);
}
@@ -839,6 +861,8 @@ static int ncm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
net = gether_connect(&ncm->port);
if (IS_ERR(net))
return PTR_ERR(net);
+ ncm->netdev = net;
+ ncm->timer_stopping = false;
}

spin_lock(&ncm->lock);
@@ -865,95 +889,232 @@ static int ncm_get_alt(struct usb_function *f, unsigned intf)
return ncm->port.in_ep->driver_data ? 1 : 0;
}

+static struct sk_buff *package_for_tx(struct f_ncm *ncm)
+{
+ __le16 *ntb_iter;
+ struct sk_buff *skb2 = NULL;
+ unsigned ndp_pad;
+ unsigned ndp_index;
+ unsigned new_len;
+
+ const struct ndp_parser_opts *opts = ncm->parser_opts;
+ const int ndp_align = le16_to_cpu(ntb_parameters.wNdpInAlignment);
+ const int dgram_idx_len = 2 * 2 * opts->dgram_item_len;
+
+ /* Stop the timer */
+ hrtimer_try_to_cancel(&ncm->task_timer);
+
+ ndp_pad = ALIGN(ncm->skb_tx_data->len, ndp_align) -
+ ncm->skb_tx_data->len;
+ ndp_index = ncm->skb_tx_data->len + ndp_pad;
+ new_len = ndp_index + dgram_idx_len + ncm->skb_tx_ndp->len;
+
+ /* Set the final BlockLength and wNdpIndex */
+ ntb_iter = (void *) ncm->skb_tx_data->data;
+ /* Increment pointer to BlockLength */
+ ntb_iter += 2 + 1 + 1;
+ put_ncm(&ntb_iter, opts->block_length, new_len);
+ put_ncm(&ntb_iter, opts->ndp_index, ndp_index);
+
+ /* Set the final NDP wLength */
+ new_len = opts->ndp_size +
+ (ncm->ndp_dgram_count * dgram_idx_len);
+ ncm->ndp_dgram_count = 0;
+ /* Increment from start to wLength */
+ ntb_iter = (void *) ncm->skb_tx_ndp->data;
+ ntb_iter += 2;
+ put_unaligned_le16(new_len, ntb_iter);
+
+ /* Merge the skbs */
+ swap(skb2, ncm->skb_tx_data);
+ if (ncm->skb_tx_data) {
+ dev_kfree_skb_any(ncm->skb_tx_data);
+ ncm->skb_tx_data = NULL;
+ }
+
+ /* Insert NDP alignment. */
+ ntb_iter = (void *) skb_put(skb2, ndp_pad);
+ memset(ntb_iter, 0, ndp_pad);
+
+ /* Copy NTB across. */
+ ntb_iter = (void *) skb_put(skb2, ncm->skb_tx_ndp->len);
+ memcpy(ntb_iter, ncm->skb_tx_ndp->data, ncm->skb_tx_ndp->len);
+ dev_kfree_skb_any(ncm->skb_tx_ndp);
+ ncm->skb_tx_ndp = NULL;
+
+ /* Insert zero'd datagram. */
+ ntb_iter = (void *) skb_put(skb2, dgram_idx_len);
+ memset(ntb_iter, 0, dgram_idx_len);
+
+ return skb2;
+}
+
static struct sk_buff *ncm_wrap_ntb(struct gether *port,
struct sk_buff *skb)
{
struct f_ncm *ncm = func_to_ncm(&port->func);
- struct sk_buff *skb2;
+ struct sk_buff *skb2 = NULL;
int ncb_len = 0;
- __le16 *tmp;
- int div;
- int rem;
- int pad;
- int ndp_align;
- int ndp_pad;
+ __le16 *ntb_data;
+ __le16 *ntb_ndp;
+ int dgram_pad;
+
unsigned max_size = ncm->port.fixed_in_len;
const struct ndp_parser_opts *opts = ncm->parser_opts;
- unsigned crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;
-
- div = le16_to_cpu(ntb_parameters.wNdpInDivisor);
- rem = le16_to_cpu(ntb_parameters.wNdpInPayloadRemainder);
- ndp_align = le16_to_cpu(ntb_parameters.wNdpInAlignment);
-
- ncb_len += opts->nth_size;
- ndp_pad = ALIGN(ncb_len, ndp_align) - ncb_len;
- ncb_len += ndp_pad;
- ncb_len += opts->ndp_size;
- ncb_len += 2 * 2 * opts->dgram_item_len; /* Datagram entry */
- ncb_len += 2 * 2 * opts->dgram_item_len; /* Zero datagram entry */
- pad = ALIGN(ncb_len, div) + rem - ncb_len;
- ncb_len += pad;
+ const int ndp_align = le16_to_cpu(ntb_parameters.wNdpInAlignment);
+ const int div = le16_to_cpu(ntb_parameters.wNdpInDivisor);
+ const int rem = le16_to_cpu(ntb_parameters.wNdpInPayloadRemainder);
+ const int dgram_idx_len = 2 * 2 * opts->dgram_item_len;

- if (ncb_len + skb->len + crc_len > max_size) {
- dev_kfree_skb_any(skb);
+ if (!skb && !ncm->skb_tx_data)
return NULL;
- }

- skb2 = skb_copy_expand(skb, ncb_len,
- max_size - skb->len - ncb_len - crc_len,
- GFP_ATOMIC);
- dev_kfree_skb_any(skb);
- if (!skb2)
- return NULL;
+ if (skb) {
+ /* Add the CRC if required up front */
+ if (ncm->is_crc) {
+ uint32_t crc;
+ __le16 *crc_pos;
+
+ crc = ~crc32_le(~0,
+ skb->data,
+ skb->len);
+ crc_pos = (void *) skb_put(skb, sizeof(uint32_t));
+ put_unaligned_le32(crc, crc_pos);
+ }

- skb = skb2;
+ /* If the new skb is too big for the current NCM NTB then
+ * set the current stored skb to be sent now and clear it
+ * ready for new data.
+ * NOTE: Assume maximum align for speed of calculation.
+ */
+ if (ncm->skb_tx_data
+ && (ncm->ndp_dgram_count >= TX_MAX_NUM_DPE
+ || (ncm->skb_tx_data->len +
+ div + rem + skb->len +
+ ncm->skb_tx_ndp->len + ndp_align + (2 * dgram_idx_len))
+ > max_size)) {
+ skb2 = package_for_tx(ncm);
+ if (!skb2)
+ goto err;
+ }

- tmp = (void *) skb_push(skb, ncb_len);
- memset(tmp, 0, ncb_len);
+ if (!ncm->skb_tx_data) {
+ ncb_len = opts->nth_size;
+ dgram_pad = ALIGN(ncb_len, div) + rem - ncb_len;
+ ncb_len += dgram_pad;

- put_unaligned_le32(opts->nth_sign, tmp); /* dwSignature */
- tmp += 2;
- /* wHeaderLength */
- put_unaligned_le16(opts->nth_size, tmp++);
- tmp++; /* skip wSequence */
- put_ncm(&tmp, opts->block_length, skb->len); /* (d)wBlockLength */
- /* (d)wFpIndex */
- /* the first pointer is right after the NTH + align */
- put_ncm(&tmp, opts->fp_index, opts->nth_size + ndp_pad);
+ /* Create a new skb for the NTH and datagrams. */
+ ncm->skb_tx_data = alloc_skb(max_size, GFP_ATOMIC);
+ if (!ncm->skb_tx_data)
+ goto err;

- tmp = (void *)tmp + ndp_pad;
+ ntb_data = (void *) skb_put(ncm->skb_tx_data, ncb_len);
+ memset(ntb_data, 0, ncb_len);
+ /* dwSignature */
+ put_unaligned_le32(opts->nth_sign, ntb_data);
+ ntb_data += 2;
+ /* wHeaderLength */
+ put_unaligned_le16(opts->nth_size, ntb_data++);
+
+ /* Allocate an skb for storing the NDP,
+ * TX_MAX_NUM_DPE should easily suffice for a
+ * 16k packet.
+ */
+ ncm->skb_tx_ndp = alloc_skb((int)(opts->ndp_size
+ + opts->dpe_size
+ * TX_MAX_NUM_DPE),
+ GFP_ATOMIC);
+ if (!ncm->skb_tx_ndp)
+ goto err;
+ ntb_ndp = (void *) skb_put(ncm->skb_tx_ndp,
+ opts->ndp_size);
+ memset(ntb_ndp, 0, ncb_len);
+ /* dwSignature */
+ put_unaligned_le32(ncm->ndp_sign, ntb_ndp);
+ ntb_ndp += 2;

- /* NDP */
- put_unaligned_le32(ncm->ndp_sign, tmp); /* dwSignature */
- tmp += 2;
- /* wLength */
- put_unaligned_le16(ncb_len - opts->nth_size - pad, tmp++);
+ /* There is always a zeroed entry */
+ ncm->ndp_dgram_count = 1;

- tmp += opts->reserved1;
- tmp += opts->next_fp_index; /* skip reserved (d)wNextFpIndex */
- tmp += opts->reserved2;
+ /* Note: we skip opts->next_ndp_index */
+ }

- if (ncm->is_crc) {
- uint32_t crc;
+ /* Delay the timer. */
+ hrtimer_start(&ncm->task_timer,
+ ktime_set(0, TX_TIMEOUT_NSECS),
+ HRTIMER_MODE_REL);
+
+ /* Add the datagram position entries */
+ ntb_ndp = (void *) skb_put(ncm->skb_tx_ndp, dgram_idx_len);
+ memset(ntb_ndp, 0, dgram_idx_len);
+
+ ncb_len = ncm->skb_tx_data->len;
+ dgram_pad = ALIGN(ncb_len, div) + rem - ncb_len;
+ ncb_len += dgram_pad;
+
+ /* (d)wDatagramIndex */
+ put_ncm(&ntb_ndp, opts->dgram_item_len, ncb_len);
+ /* (d)wDatagramLength */
+ put_ncm(&ntb_ndp, opts->dgram_item_len, skb->len);
+ ncm->ndp_dgram_count++;
+
+ /* Add the new data to the skb */
+ ntb_data = (void *) skb_put(ncm->skb_tx_data, dgram_pad);
+ memset(ntb_data, 0, dgram_pad);
+ ntb_data = (void *) skb_put(ncm->skb_tx_data, skb->len);
+ memcpy(ntb_data, skb->data, skb->len);
+ dev_kfree_skb_any(skb);
+ skb = NULL;

- crc = ~crc32_le(~0,
- skb->data + ncb_len,
- skb->len - ncb_len);
- put_unaligned_le32(crc, skb->data + skb->len);
- skb_put(skb, crc_len);
+ } else if (ncm->skb_tx_data && ncm->timer_force_tx) {
+ /* If the tx was requested because of a timeout then send */
+ skb2 = package_for_tx(ncm);
+ if (!skb2)
+ goto err;
}

- /* (d)wDatagramIndex[0] */
- put_ncm(&tmp, opts->dgram_item_len, ncb_len);
- /* (d)wDatagramLength[0] */
- put_ncm(&tmp, opts->dgram_item_len, skb->len - ncb_len);
- /* (d)wDatagramIndex[1] and (d)wDatagramLength[1] already zeroed */
+ return skb2;
+
+err:
+ ncm->netdev->stats.tx_dropped++;
+
+ if (skb)
+ dev_kfree_skb_any(skb);
+ if (ncm->skb_tx_data)
+ dev_kfree_skb_any(ncm->skb_tx_data);
+ if (ncm->skb_tx_ndp)
+ dev_kfree_skb_any(ncm->skb_tx_ndp);
+
+ return NULL;
+}
+
+/*
+ * This transmits the NTB if there are frames waiting.
+ */
+static void ncm_tx_tasklet(unsigned long data)
+{
+ struct f_ncm *ncm = (void *)data;

- if (skb->len > MAX_TX_NONFIXED)
- memset(skb_put(skb, max_size - skb->len),
- 0, max_size - skb->len);
+ if (ncm->timer_stopping)
+ return;
+
+ /* Only send if data is available. */
+ if (ncm->skb_tx_data) {
+ ncm->timer_force_tx = true;
+ ncm->netdev->netdev_ops->ndo_start_xmit(NULL, ncm->netdev);
+ ncm->timer_force_tx = false;
+ }
+}

- return skb;
+/*
+ * The transmit should only be run if no skb data has been sent
+ * for a certain duration.
+ */
+static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
+{
+ struct f_ncm *ncm = container_of(data, struct f_ncm, task_timer);
+ tasklet_schedule(&ncm->tx_tasklet);
+ return HRTIMER_NORESTART;
}

static int ncm_unwrap_ntb(struct gether *port,
@@ -996,7 +1157,7 @@ static int ncm_unwrap_ntb(struct gether *port,
goto err;
}

- ndp_index = get_ncm(&tmp, opts->fp_index);
+ ndp_index = get_ncm(&tmp, opts->ndp_index);

/* Run through all the NDP's in the NTB */
do {
@@ -1033,7 +1194,7 @@ static int ncm_unwrap_ntb(struct gether *port,
}
tmp += opts->reserved1;
/* Check for another NDP (d)wNextNdpIndex */
- ndp_index = get_ncm(&tmp, opts->next_fp_index);
+ ndp_index = get_ncm(&tmp, opts->next_ndp_index);
tmp += opts->reserved2;

ndp_len -= opts->ndp_size;
@@ -1107,8 +1268,11 @@ static void ncm_disable(struct usb_function *f)

DBG(cdev, "ncm deactivated\n");

- if (ncm->port.in_ep->driver_data)
+ if (ncm->port.in_ep->driver_data) {
+ ncm->timer_stopping = true;
+ ncm->netdev = NULL;
gether_disconnect(&ncm->port);
+ }

if (ncm->notify->driver_data) {
usb_ep_disable(ncm->notify);
@@ -1277,6 +1441,10 @@ static int ncm_bind(struct usb_configuration *c, struct usb_function *f)
ncm->port.open = ncm_open;
ncm->port.close = ncm_close;

+ tasklet_init(&ncm->tx_tasklet, ncm_tx_tasklet, (unsigned long) ncm);
+ hrtimer_init(&ncm->task_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ ncm->task_timer.function = ncm_tx_timeout;
+
DBG(cdev, "CDC Network: %s speed IN/%s OUT/%s NOTIFY/%s\n",
gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
ncm->port.in_ep->name, ncm->port.out_ep->name,
@@ -1390,6 +1558,10 @@ static void ncm_unbind(struct usb_configuration *c, struct usb_function *f)

DBG(c->cdev, "ncm unbind\n");

+ hrtimer_cancel(&ncm->task_timer);
+ tasklet_kill(&ncm->tx_tasklet);
+
+ ncm_string_defs[0].id = 0;
usb_free_all_descriptors(f);

kfree(ncm->notify_req->buf);
@@ -1426,6 +1598,7 @@ static struct usb_function *ncm_alloc(struct usb_function_instance *fi)
ncm->port.ioport = netdev_priv(opts->net);
mutex_unlock(&opts->lock);
ncm->port.is_fixed = true;
+ ncm->port.supports_multi_frame = true;

ncm->port.func.name = "cdc_network";
/* descriptors are per-instance copies */
diff --git a/drivers/usb/gadget/u_ether.c b/drivers/usb/gadget/u_ether.c
index 97b0277..d50adda 100644
--- a/drivers/usb/gadget/u_ether.c
+++ b/drivers/usb/gadget/u_ether.c
@@ -483,7 +483,7 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
struct net_device *net)
{
struct eth_dev *dev = netdev_priv(net);
- int length = skb->len;
+ int length = 0;
int retval;
struct usb_request *req = NULL;
unsigned long flags;
@@ -500,13 +500,13 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
}
spin_unlock_irqrestore(&dev->lock, flags);

- if (!in) {
+ if (skb && !in) {
dev_kfree_skb_any(skb);
return NETDEV_TX_OK;
}

/* apply outgoing CDC or RNDIS filters */
- if (!is_promisc(cdc_filter)) {
+ if (skb && !is_promisc(cdc_filter)) {
u8 *dest = skb->data;

if (is_multicast_ether_addr(dest)) {
@@ -557,11 +557,17 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
if (dev->port_usb)
skb = dev->wrap(dev->port_usb, skb);
spin_unlock_irqrestore(&dev->lock, flags);
- if (!skb)
+ if (!skb) {
+ /* Multi frame CDC protocols may store the frame for
+ * later which is not a dropped frame.
+ */
+ if (dev->port_usb->supports_multi_frame)
+ goto multiframe;
goto drop;
-
- length = skb->len;
+ }
}
+
+ length = skb->len;
req->buf = skb->data;
req->context = skb;
req->complete = tx_complete;
@@ -604,6 +610,7 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
dev_kfree_skb_any(skb);
drop:
dev->net->stats.tx_dropped++;
+multiframe:
spin_lock_irqsave(&dev->req_lock, flags);
if (list_empty(&dev->tx_reqs))
netif_start_queue(net);
diff --git a/drivers/usb/gadget/u_ether.h b/drivers/usb/gadget/u_ether.h
index 0f0290a..334b389 100644
--- a/drivers/usb/gadget/u_ether.h
+++ b/drivers/usb/gadget/u_ether.h
@@ -18,6 +18,7 @@
#include <linux/if_ether.h>
#include <linux/usb/composite.h>
#include <linux/usb/cdc.h>
+#include <linux/netdevice.h>

#include "gadget_chips.h"

@@ -74,6 +75,7 @@ struct gether {
bool is_fixed;
u32 fixed_out_len;
u32 fixed_in_len;
+ bool supports_multi_frame;
struct sk_buff *(*wrap)(struct gether *port,
struct sk_buff *skb);
int (*unwrap)(struct gether *port,
--
1.7.9.5

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