netdev - Re: [PATCH v3] net: macb: restart tx after tx used bit read

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Date:   Tue, 18 Dec 2018 15:58:07 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     Claudiu.Beznea@...rochip.com
Cc:     Nicolas.Ferre@...rochip.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] net: macb: restart tx after tx used bit read

From: <Claudiu.Beznea@...rochip.com>
Date: Mon, 17 Dec 2018 10:02:42 +0000

> From: Claudiu Beznea <claudiu.beznea@...rochip.com>
> 
> On some platforms (currently detected only on SAMA5D4) TX might stuck
> even the pachets are still present in DMA memories and TX start was
> issued for them. This happens due to race condition between MACB driver
> updating next TX buffer descriptor to be used and IP reading the same
> descriptor. In such a case, the "TX USED BIT READ" interrupt is asserted.
> GEM/MACB user guide specifies that if a "TX USED BIT READ" interrupt
> is asserted TX must be restarted. Restart TX if used bit is read and
> packets are present in software TX queue. Packets are removed from software
> TX queue if TX was successful for them (see macb_tx_interrupt()).
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>

Applied and queued up for -stable, thanks.