netdev - Re: [PATCH] macb: avoid lockup when TGO during underrun

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Date:	Sun, 18 Jan 2009 21:57:49 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	richard.rojfors@...ian.se
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] macb: avoid lockup when TGO during underrun

From: Richard Röjfors <richard.rojfors@...ian.se>
Date: Thu, 15 Jan 2009 19:30:16 +0100

> This patch against linux-2.6.28 solves an issue where macb might run out of TX buffers.
> 
> In rare cases when an underrun occur, all macb buffers where consumed and the netif_queue was stopped infinitely. This
> happens then the TGO (transfer ongoing) bit in the TSR is set (and UND). It seems like clening up after the underrun
> makes the driver and the macb hardware end up in an inconsistent state. The result of this is that in the following
> calls to macb_tx no TX buffers are released -> the netif_queue was stopped, and never woken up again.
> 
> The solution is to disable the transmitter, if TGO is set, before clening up after the underrun, and re-enable the
> transmitter when the cleaning up is done.
> 
> 
> A patch to avoid lockup in the macb driver in some rare underrun cases.
> Signed-off-by: Richard Röjfors <richard.rojfors@...ian.se>

Patch applied, thanks Richard.
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