On Tue, Nov 01, 2016 at 01:29:59PM +0200, Felipe Balbi wrote:
> According to Dave Miller "the networking stack has a
> hard requirement that all SKBs which are transmitted
> must have their completion signalled in a fininte
> amount of time. This is because, until the SKB is
> freed by the driver, it holds onto socket,
> netfilter, and other subsystem resources."
>
> In summary, this means that using TX IRQ throttling
> for the networking gadgets is, at least, complex and
> we should avoid it for the time being.
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Reported-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Suggested-by: David Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Fixes laggy/hangy g_ether on my BYT FFRD8 tablet, caused by
commit 55a0237f8f47 ("usb: dwc3: gadget: use allocated/queued reqs for LST bit")
Tested-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/usb/gadget/function/u_ether.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
> index f4a640216913..119a2e5848e8 100644
> --- a/drivers/usb/gadget/function/u_ether.c
> +++ b/drivers/usb/gadget/function/u_ether.c
> @@ -589,14 +589,6 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
>
> req->length = length;
>
> - /* throttle high/super speed IRQ rate back slightly */
> - if (gadget_is_dualspeed(dev->gadget))
> - req->no_interrupt = (((dev->gadget->speed == USB_SPEED_HIGH ||
> - dev->gadget->speed == USB_SPEED_SUPER)) &&
> - !list_empty(&dev->tx_reqs))
> - ? ((atomic_read(&dev->tx_qlen) % dev->qmult) != 0)
> - : 0;
> -
> retval = usb_ep_queue(in, req, GFP_ATOMIC);
> switch (retval) {
> default:
> --
> 2.10.1
--
Ville Syrjälä
Intel OTC
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