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?
>
> Signed-off-by: Kedareswara rao Appana <appanad@xxxxxxxxxx>
> ---
> 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...
> 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
>
> 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
>
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--
~Vinod
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