linux-kernel - Re: [PATCH 2/8] dmaengine: hisilicon: Fix CQ head update

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Message-ID: <YrnrGfIAk7wCnEY2@matsya>
Date:   Mon, 27 Jun 2022 23:08:33 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     haijie <haijie1@...wei.com>
Cc:     "Wangzhou (B)" <wangzhou1@...ilicon.com>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/8] dmaengine: hisilicon: Fix CQ head update

On 27-06-22, 07:01, haijie wrote:
> Hi, Vinod,
> 
> This happens bacause I rearranged this patch without checking, it will be corrected in v2.

Please _do_ _not_ top post and reply inline to the queries. Otherwise it
is very difficult to understand...

> 
> Thanks.
> 
> -----Original Message-----
> From: Vinod Koul [mailto:vkoul@...nel.org] 
> Sent: Monday, June 27, 2022 2:13 PM
> To: haijie <haijie1@...wei.com>
> Cc: Wangzhou (B) <wangzhou1@...ilicon.com>; dmaengine@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 2/8] dmaengine: hisilicon: Fix CQ head update
> 
> On 25-06-22, 15:44, Jie Hai wrote:
> > After completion of data transfer of one or multiple descriptors, the 
> > completion status and the current head pointer to submission queue are 
> > written into the CQ and interrupt can be generated to inform the 
> > software. In interrupt process CQ is read and cq_head is updated.
> > 
> > hisi_dma_irq updates cq_head only when the completion status is 
> > success. When an abnormal interrupt reports, cq_head will not update 
> > which will cause subsequent interrupt processes read the error CQ and 
> > never report the correct status.
> > 
> > This patch updates cq_head whenever CQ is accessed.
> > 
> > Fixes: e9f08b65250d ("dmaengine: hisilicon: Add Kunpeng DMA engine 
> > support")
> > 
> 
> No need for blank line
> > Signed-off-by: Jie Hai <haijie1@...wei.com>
> > ---
> >  drivers/dma/hisi_dma.c | 9 ++++-----
> >  1 file changed, 4 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/dma/hisi_dma.c b/drivers/dma/hisi_dma.c index 
> > 98bc488893cc..0a0f8a4d168a 100644
> > --- a/drivers/dma/hisi_dma.c
> > +++ b/drivers/dma/hisi_dma.c
> > @@ -436,12 +436,11 @@ static irqreturn_t hisi_dma_irq(int irq, void *data)
> >  	desc = chan->desc;
> >  	cqe = chan->cq + chan->cq_head;
> >  	if (desc) {
> > +		chan->cq_head = (chan->cq_head + 1) %
> > +				hdma_dev->chan_depth;
> > +		hisi_dma_chan_write(q_base, HISI_DMA_Q_CQ_HEAD_PTR,
> 
> q_base?
> 
> --
> ~Vinod

-- 
~Vinod