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Maciej Żenczykowski 1958ff5ad2 usb: f_ncm: only first packet of aggregate needs to start timer

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 <brookebasile@gmail.com>
Cc: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Link: https://lore.kernel.org/r/20210608085438.813960-1-zenczykowski@gmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2021-06-09 10:34:18 +02:00

function

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

2021-06-09 10:34:18 +02:00

legacy

usb: gadget: prevent a ternary sign expansion bug

2021-04-22 13:17:29 +02:00

udc

usb: gadget: udc: renesas_usb3: Fix a race in usb3_start_pipen()

2021-05-24 15:22:28 +02:00

composite.c

usb: gadget: composite: Report various SSP sublink speeds