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Date: Wed, 11 Nov 2015 14:13:11 -0500 (EST)
From: David Miller <davem@...emloft.net>
To: mans@...sr.com
Cc: romieu@...zoreil.com, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, slash.tmp@...e.fr
Subject: Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800
Ethernet controller
From: Måns Rullgård <mans@...sr.com>
Date: Wed, 11 Nov 2015 19:09:19 +0000
> David Miller <davem@...emloft.net> writes:
>
>> From: Måns Rullgård <mans@...sr.com>
>> 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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