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Message-ID: <C246CAC1457055469EF09E3A7AC4E11A4A561D18@XAP-PVEXMBX01.xlnx.xilinx.com>
Date: Tue, 23 Feb 2016 04:19:03 +0000
From: Appana Durga Kedareswara Rao <appana.durga.rao@...inx.com>
To: Vinod Koul <vinod.koul@...el.com>
CC: "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
Michal Simek <michals@...inx.com>,
Soren Brinkmann <sorenb@...inx.com>,
"moritz.fischer@...us.com" <moritz.fischer@...us.com>,
"laurent.pinchart@...asonboard.com"
<laurent.pinchart@...asonboard.com>,
"luis@...ethencourt.com" <luis@...ethencourt.com>,
Anirudha Sarangi <anirudh@...inx.com>,
"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 2/4] dmaengine: xilinx_vdma: Simplify spin lock
handling
Hi Vinod,
> -----Original Message-----
> From: Vinod Koul [mailto:vinod.koul@...el.com]
> Sent: Tuesday, February 23, 2016 8:40 AM
> To: Appana Durga Kedareswara Rao
> Cc: dan.j.williams@...el.com; Michal Simek; Soren Brinkmann; Appana Durga
> Kedareswara Rao; moritz.fischer@...us.com;
> laurent.pinchart@...asonboard.com; luis@...ethencourt.com; Anirudha
> Sarangi; dmaengine@...r.kernel.org; linux-arm-kernel@...ts.infradead.org;
> linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v2 2/4] dmaengine: xilinx_vdma: Simplify spin lock handling
>
> On Mon, Feb 22, 2016 at 11:24:35AM +0530, Kedareswara rao Appana wrote:
> > This patch simplifies the spin lock handling in the driver.
>
> But sadly doesn't describe how?
Ok sure will improve commit message in the next version.
>
> >
> > Signed-off-by: Kedareswara rao Appana <appanad@...inx.com>
> > ---
> > Changes for v2:
> > ---> splitted the changes into multiple patches.
> >
> > drivers/dma/xilinx/xilinx_vdma.c | 27 ++++++++++-----------------
> > 1 file changed, 10 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/dma/xilinx/xilinx_vdma.c
> > b/drivers/dma/xilinx/xilinx_vdma.c
> > index 06bffec..d646218 100644
> > --- a/drivers/dma/xilinx/xilinx_vdma.c
> > +++ b/drivers/dma/xilinx/xilinx_vdma.c
> > @@ -605,17 +605,14 @@ static void xilinx_vdma_start_transfer(struct
> > xilinx_vdma_chan *chan) {
> > struct xilinx_vdma_config *config = &chan->config;
> > struct xilinx_vdma_tx_descriptor *desc, *tail_desc;
> > - unsigned long flags;
> > u32 reg;
> > struct xilinx_vdma_tx_segment *tail_segment;
> >
> > if (chan->err)
> > return;
> >
> > - spin_lock_irqsave(&chan->lock, flags);
> > -
>
> It would help if you add a comment to this function taht we need to invoke this
> with lock held...
Ok sure will add comment..
>
> > if (list_empty(&chan->pending_list))
> > - goto out_unlock;
> > + return;
> >
> > desc = list_first_entry(&chan->pending_list,
> > struct xilinx_vdma_tx_descriptor, node); @@ -
> 629,7 +626,7 @@
> > static void xilinx_vdma_start_transfer(struct xilinx_vdma_chan *chan)
> > if (chan->has_sg && xilinx_vdma_is_running(chan) &&
> > !xilinx_vdma_is_idle(chan)) {
> > dev_dbg(chan->dev, "DMA controller still busy\n");
> > - goto out_unlock;
> > + return;
> > }
> >
> > /*
> > @@ -676,7 +673,7 @@ static void xilinx_vdma_start_transfer(struct
> xilinx_vdma_chan *chan)
> > xilinx_vdma_start(chan);
> >
> > if (chan->err)
> > - goto out_unlock;
> > + return;
> >
> > /* Start the transfer */
> > if (chan->has_sg) {
> > @@ -696,7 +693,7 @@ static void xilinx_vdma_start_transfer(struct
> xilinx_vdma_chan *chan)
> > }
> >
> > if (!last)
> > - goto out_unlock;
> > + return;
> >
> > /* HW expects these parameters to be same for one
> transaction */
> > vdma_desc_write(chan, XILINX_VDMA_REG_HSIZE, last-
> >hw.hsize); @@
> > -707,9 +704,6 @@ static void xilinx_vdma_start_transfer(struct
> > xilinx_vdma_chan *chan)
> >
> > list_splice_tail_init(&chan->pending_list, &chan->active_list);
> > chan->desc_pendingcount = 0;
> > -
> > -out_unlock:
> > - spin_unlock_irqrestore(&chan->lock, flags);
> > }
> >
> > /**
> > @@ -719,8 +713,11 @@ out_unlock:
> > static void xilinx_vdma_issue_pending(struct dma_chan *dchan) {
> > struct xilinx_vdma_chan *chan = to_xilinx_chan(dchan);
> > + unsigned long flags;
> >
> > + spin_lock_irqsave(&chan->lock, flags);
> > xilinx_vdma_start_transfer(chan);
> > + spin_unlock_irqrestore(&chan->lock, flags);
> > }
> >
> > /**
> > @@ -732,21 +729,15 @@ static void xilinx_vdma_issue_pending(struct
> > dma_chan *dchan) static void xilinx_vdma_complete_descriptor(struct
> > xilinx_vdma_chan *chan) {
> > struct xilinx_vdma_tx_descriptor *desc, *next;
> > - unsigned long flags;
> > -
> > - spin_lock_irqsave(&chan->lock, flags);
>
> this one as well
Ok sure will add comment..
Regards,
Kedar.
>
> >
> > if (list_empty(&chan->active_list))
> > - goto out_unlock;
> > + return;
> >
> > list_for_each_entry_safe(desc, next, &chan->active_list, node) {
> > list_del(&desc->node);
> > dma_cookie_complete(&desc->async_tx);
> > list_add_tail(&desc->node, &chan->done_list);
> > }
> > -
> > -out_unlock:
> > - spin_unlock_irqrestore(&chan->lock, flags);
> > }
> >
> > /**
> > @@ -857,8 +848,10 @@ static irqreturn_t xilinx_vdma_irq_handler(int irq,
> void *data)
> > }
> >
> > if (status & XILINX_VDMA_DMASR_FRM_CNT_IRQ) {
> > + spin_lock(&chan->lock);
> > xilinx_vdma_complete_descriptor(chan);
> > xilinx_vdma_start_transfer(chan);
> > + spin_unlock(&chan->lock);
> > }
> >
> > tasklet_schedule(&chan->tasklet);
> > --
> > 2.1.2
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe dmaengine"
> > in the body of a message to majordomo@...r.kernel.org More majordomo
> > info at http://vger.kernel.org/majordomo-info.html
>
> --
> ~Vinod
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