Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller

[David Miller]

From: Måns Rullgård <mans@xxxxxxxxx>
Date: Wed, 11 Nov 2015 19:09:19 +0000

> David Miller <davem@xxxxxxxxxxxxx> writes:
> 
>> From: Måns Rullgård <mans@xxxxxxxxx>
>> Date: Wed, 11 Nov 2015 18:25:05 +0000
>>
>>> If the TX DMA channel is idle when start_xmit is called, it can be
>>> started immediately.  Checking the DMA status and starting it if
>>> idle has to be done atomically somehow.
>>
>> ->ndo_start_xmit() is guaranteed to be invoked atomically, protected
>> by the TX queue spinlock.
> 
> Yes, but the DMA needs to be restarted from some other context if it was
> busy when start_xmit checked.

Then you can probably use the TXQ lock in the interrupt handler just for
that.
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