Re: [PATCH] usb: gadget: u_ether: remove interrupt throttling

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From: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Date: Mon, 07 Nov 2016 14:39:21 +0200

> 
> Hi,
> 
> David Miller <davem@xxxxxxxxxxxxx> writes:
>> From: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
>> Date: Thu, 03 Nov 2016 09:04:54 +0200
>>
>>> What Dave Miller is saying is that it's ALWAYS a bug to delay
>>> completion of SKBs. The only thing you're doing with chipidea is
>>> delaying interrupt by up to 125us; which is still a bug from the
>>> point of view of the networking layer, but it's more difficult to
>>> perceive any problems because of the short time where interrupt is
>>> delayed.
>>
>> I didn't say delaying was illegal.
>>
>> I said that the SKB free must occur in a reasonable, finite, amount of
>> time.
> 
> "reasonable" is rather subjective. Completions are, of course,
> finite. It just means that once a transfer completes *and* has interrupt
> enabled, then several other SKBs will be completed along with it.
> 
> That doesn't mean *all* SKBs completed at the same time, it means once
> we get an interrupt, we give back all previous ones, but we don't know
> exactly when they completed.

I think you know what I was trying to say which is that
some event is guaranteed to release the SKBs on some order
of magnitude less than say half a second.
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