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SubjectRe: [LINUX PATCH 2/4] dmaengine: xilinx_dma: Fix race condition in the driver for cdma
On Thu, Dec 21, 2017 at 03:41:36PM +0530, Kedareswara rao Appana wrote:

same issue for patch title here too

> when hardware is idle we need to toggle the SG bit
> in the control register, inorder to update new value to the
> current descriptor register other wise undefined
> results will occur.

can you try making it bit more clear..

>
> This patch updates the same.
>
> Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
> ---
> drivers/dma/xilinx/xilinx_dma.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
> index 21ac954..8467671 100644
> --- a/drivers/dma/xilinx/xilinx_dma.c
> +++ b/drivers/dma/xilinx/xilinx_dma.c
> @@ -1204,6 +1204,12 @@ static void xilinx_cdma_start_transfer(struct xilinx_dma_chan *chan)
> }
>
> if (chan->has_sg) {
> + dma_ctrl_clr(chan, XILINX_DMA_REG_DMACR,
> + XILINX_CDMA_CR_SGMODE);
> +
> + dma_ctrl_set(chan, XILINX_DMA_REG_DMACR,
> + XILINX_CDMA_CR_SGMODE);
> +
> xilinx_write(chan, XILINX_DMA_REG_CURDESC,
> head_desc->async_tx.phys);
>
> @@ -2052,6 +2058,10 @@ static int xilinx_dma_terminate_all(struct dma_chan *dchan)
> chan->cyclic = false;
> }
>
> + if ((chan->xdev->dma_config->dmatype == XDMA_TYPE_CDMA) && chan->has_sg)
> + dma_ctrl_clr(chan, XILINX_DMA_REG_DMACR,
> + XILINX_CDMA_CR_SGMODE);
> +
> return 0;
> }
>
> --
> 2.7.4
>

--
~Vinod

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