Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller
From: Måns Rullgård
Date: Wed Nov 11 2015 - 14:17:15 EST
David Miller <davem@xxxxxxxxxxxxx> writes:
> 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 seems a bit heavy-handed when the critical section for this is only
a tiny part of the start_xmit function.
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