From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ivan Khoronzhuk Subject: Re: [PATCH 2/7] net: ethernet: ti: cpdma: fix desc re-queuing Date: Fri, 2 Dec 2016 13:03:22 +0200 Message-ID: <20161202110321.GA1213@khorivan> References: <20161201233432.6182-1-grygorii.strashko@ti.com> <20161201233432.6182-3-grygorii.strashko@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S. Miller" , netdev@vger.kernel.org, Mugunthan V N , Sekhar Nori , linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org To: Grygorii Strashko Return-path: Content-Disposition: inline In-Reply-To: <20161201233432.6182-3-grygorii.strashko@ti.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Dec 01, 2016 at 05:34:27PM -0600, Grygorii Strashko wrote: > The currently processing cpdma descriptor with EOQ flag set may > contain two values in Next Descriptor Pointer field: > - valid pointer: means CPDMA missed addition of new desc in queue; It shouldn't happen in normal circumstances, right? So, why it happens only for egress channels? And Does that mean there is some resynchronization between submit and process function, or this is h/w issue? > - null: no more descriptors in queue. > In the later case, it's not required to write to HDP register, but now > CPDMA does it. > > Hence, add additional check for Next Descriptor Pointer != null in > cpdma_chan_process() function before writing in HDP register. > > Signed-off-by: Grygorii Strashko > --- > drivers/net/ethernet/ti/davinci_cpdma.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c > index 0924014..379314f 100644 > --- a/drivers/net/ethernet/ti/davinci_cpdma.c > +++ b/drivers/net/ethernet/ti/davinci_cpdma.c > @@ -1152,7 +1152,7 @@ static int __cpdma_chan_process(struct cpdma_chan *chan) > chan->count--; > chan->stats.good_dequeue++; > > - if (status & CPDMA_DESC_EOQ) { > + if ((status & CPDMA_DESC_EOQ) && chan->head) { > chan->stats.requeue++; > chan_write(chan, hdp, desc_phys(pool, chan->head)); > } > -- > 2.10.1 >