linux.git/drivers/usb/gadget/function/f_ncm.c, branch v5.17

usb: gadget: f_ncm: ncm_wrap_ntb - move var definitions into if statement

2021-07-21T08:04:19+00:00

Since they're only used if there's an skb.

Cc: Brooke Basile 
Cc: "Bryan O'Donoghue" 
Cc: Felipe Balbi 
Cc: Greg Kroah-Hartman 
Cc: Lorenzo Colitti 
Signed-off-by: Maciej Żenczykowski 
Link: https://lore.kernel.org/r/20210701114834.884597-5-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_ncm: remove spurious if statement

2021-07-21T08:04:19+00:00

the current logic is:

  struct sk_buff  *skb2 = NULL;
  ...

  if (!skb && !ncm->skb_tx_data)
    return NULL;

  if (skb) {
    ...
  } else if (ncm->skb_tx_data)
    ...
  }

  return skb2;

Which means that first if statement is simply not needed.

Cc: Brooke Basile 
Cc: "Bryan O'Donoghue" 
Cc: Felipe Balbi 
Cc: Greg Kroah-Hartman 
Cc: Lorenzo Colitti 
Signed-off-by: Maciej Żenczykowski 
Link: https://lore.kernel.org/r/20210701114834.884597-4-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_ncm: remove check for NULL skb_tx_data in timer function

2021-07-21T08:04:19+00:00

This condition is already checked for in ncm_wrap_ntb(),
except that that check is done with eth_dev->lock held
(it is grabbed by eth_start_xmit).

It's best to not be reaching into ncm struct without locks held.

Cc: Brooke Basile 
Cc: "Bryan O'Donoghue" 
Cc: Felipe Balbi 
Cc: Greg Kroah-Hartman 
Cc: Lorenzo Colitti 
Signed-off-by: Maciej Żenczykowski 
Link: https://lore.kernel.org/r/20210701114834.884597-3-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_ncm: remove spurious boolean timer_stopping

2021-07-21T08:04:19+00:00

It is equivalent to ncm->netdev being NULL.

Cc: Brooke Basile 
Cc: "Bryan O'Donoghue" 
Cc: Felipe Balbi 
Cc: Greg Kroah-Hartman 
Cc: Lorenzo Colitti 
Signed-off-by: Maciej Żenczykowski 
Link: https://lore.kernel.org/r/20210701114834.884597-2-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_ncm: remove timer_force_tx field

2021-07-21T08:04:19+00:00

It is simply not needed.  This field is equivalent to skb being NULL.

Currently with the boolean set to true we call:
  ncm->netdev->netdev_ops->ndo_start_xmit(NULL, ncm->netdev);
which calls u_ether's:
  eth_start_xmit(NULL, ...)
which then calls:
  skb = dev->wrap(dev->port_usb, NULL);
which calls back into f_ncm's:
  ncm_wrap_ntb(..., NULL)

Cc: Brooke Basile 
Cc: "Bryan O'Donoghue" 
Cc: Felipe Balbi 
Cc: Greg Kroah-Hartman 
Cc: Lorenzo Colitti 
Signed-off-by: Maciej Żenczykowski 
Link: https://lore.kernel.org/r/20210701114834.884597-1-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman

usb: f_ncm: only first packet of aggregate needs to start timer

2021-06-09T08:34:18+00:00

The reasoning for this change is that if we already had
a packet pending, then we also already had a pending timer,
and as such there is no need to reschedule it.

This also prevents packets getting delayed 60 ms worst case
under a tiny packet every 290us transmit load, by keeping the
timeout always relative to the first queued up packet.
(300us delay * 16KB max aggregation / 80 byte packet =~ 60 ms)

As such the first packet is now at most delayed by 300us.

Under low transmit load, this will simply result in us sending
a shorter aggregate, as originally intended.

This patch has the benefit of greatly reducing (by ~10 factor
with 1500 byte frames aggregated into 16 kiB) the number of
(potentially pretty costly) updates to the hrtimer.

Cc: Brooke Basile 
Cc: Bryan O'Donoghue 
Cc: Felipe Balbi 
Cc: Lorenzo Colitti 
Signed-off-by: Maciej Żenczykowski 
Link: https://lore.kernel.org/r/20210608085438.813960-1-zenczykowski@gmail.com
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

USB: f_ncm: ncm_bitrate (speed) is unsigned

2021-06-09T08:26:43+00:00

[  190.544755] configfs-gadget gadget: notify speed -44967296

This is because 4250000000 - 2**32 is -44967296.

Fixes: 9f6ce4240a2b ("usb: gadget: f_ncm.c added")
Cc: Brooke Basile 
Cc: Bryan O'Donoghue 
Cc: Felipe Balbi 
Cc: Lorenzo Colitti 
Cc: Yauheni Kaliuta 
Cc: Linux USB Mailing List 
Acked-By: Lorenzo Colitti 
Signed-off-by: Maciej Żenczykowski 
Cc: stable 
Link: https://lore.kernel.org/r/20210608005344.3762668-1-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_ncm: allow using NCM in SuperSpeed Plus gadgets.

2020-10-02T06:57:41+00:00

Currently, enabling f_ncm at SuperSpeed Plus speeds results in an
oops in config_ep_by_speed because ncm_set_alt passes in NULL
ssp_descriptors. Fix this by re-using the SuperSpeed descriptors.
This is safe because usb_assign_descriptors calls
usb_copy_descriptors.

Tested: enabled f_ncm on a dwc3 gadget and 10Gbps link, ran iperf
Reviewed-by: Maciej Żenczykowski 
Signed-off-by: Lorenzo Colitti 
Signed-off-by: Felipe Balbi

usb: gadget: f_ncm: set SuperSpeed bulk descriptor bMaxBurst to 15

2020-10-02T06:57:41+00:00

This improves performance on fast connections. When directly
connecting to a Linux laptop running 5.6, single-stream iperf3
goes from ~1.7Gbps to ~2.3Gbps out, and from ~620Mbps to ~720Mbps
in.

Reviewed-by: Maciej Żenczykowski 
Signed-off-by: Lorenzo Colitti 
Signed-off-by: Felipe Balbi

usb: gadget: f_ncm: fix ncm_bitrate for SuperSpeed and above.

2020-10-02T06:57:41+00:00

Currently, SuperSpeed NCM gadgets report a speed of 851 Mbps
in USB_CDC_NOTIFY_SPEED_CHANGE. But the calculation appears to
assume 16 packets per microframe, and USB 3 and above no longer
use microframes.

Maximum speed is actually much higher. On a direct connection,
theoretical throughput is at most 3.86 Gbps for gen1x1 and
9.36 Gbps for gen2x1, and I have seen gadget->host iperf
throughput of >2 Gbps for gen1x1 and >4 Gbps for gen2x1.

Unfortunately the ConnectionSpeedChange defined in the CDC spec
only uses 32-bit values, so we can't report accurate numbers for
10Gbps and above. So, report 3.75Gbps for SuperSpeed (which is
roughly maximum theoretical performance) and 4.25Gbps for
SuperSpeed Plus (which is close to the maximum that we can report
in a 32-bit unsigned integer).

This results in:

[50879.191272] cdc_ncm 2-2:1.0 enx228b127e050c: renamed from usb0
[50879.234778] cdc_ncm 2-2:1.0 enx228b127e050c: 3750 mbit/s downlink 3750 mbit/s uplink

on SuperSpeed and:

[50798.434527] cdc_ncm 8-2:1.0 enx228b127e050c: renamed from usb0
[50798.524278] cdc_ncm 8-2:1.0 enx228b127e050c: 4250 mbit/s downlink 4250 mbit/s uplink

on SuperSpeed Plus.

Fixes: 1650113888fe ("usb: gadget: f_ncm: add SuperSpeed descriptors for CDC NCM")
Reviewed-by: Maciej Żenczykowski 
Signed-off-by: Lorenzo Colitti 
Signed-off-by: Felipe Balbi