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SubjectRe: [PATCH v4] dma: imx-sdma: switch to dynamic context mode after script loaded
On Sun, Feb 15, 2015 at 10:00:35AM +0800, Robin Gong wrote:
> Below comments got from Page4724 of Reference Manual of i.mx6q:
> http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf
>
> --"Static context mode should be used for the first channel called
> after reset to ensure that the all context RAM for that channel is
> initialized during the context SAVE phase when the channel is
> done or yields. Subsequent calls to the same channel or
> different channels may use any of the dynamic context modes.
> This will ensure that all context locations for the bootload
> channel are initialized, and prevent undefined values in context
> RAM from being loaded during the context restore if the
> channel is re-started later"
>
> Unfortunately, the rule was broken by commit(5b28aa319bba96987316425a1131813d87cbab35)
> .This patch just take them back.

Applied, thanks

--
~Vinod

>
> Signed-off-by: Robin Gong <b38343@freescale.com>
> ---
> drivers/dma/imx-sdma.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index d0df198..644cfa0 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -531,6 +531,10 @@ static int sdma_run_channel0(struct sdma_engine *sdma)
> dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
> }
>
> + /* Set bits of CONFIG register with dynamic context switching */
> + if (readl(sdma->regs + SDMA_H_CONFIG) == 0)
> + writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG);
> +
> return ret ? 0 : -ETIMEDOUT;
> }
>
> @@ -1401,9 +1405,6 @@ static int sdma_init(struct sdma_engine *sdma)
>
> writel_relaxed(ccb_phys, sdma->regs + SDMA_H_C0PTR);
>
> - /* Set bits of CONFIG register with given context switching mode */
> - writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG);
> -
> /* Initializes channel's priorities */
> sdma_set_channel_priority(&sdma->channel[0], 7);
>
> --
> 1.9.1
>
> --
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