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SubjectRe: [PATCH] dmaengine: at_xdmac: fix bug about channel configuration
Vinod,

If you have no objection about his patch, could you take it?

Thanks

Ludovic

On Wed, Jun 17, 2015 at 04:22:26PM +0200, Ludovic Desroches wrote:
> When using descriptor view 2 or higher, we don't write the configuration
> into AT_XDMAC_CC register because this configuration will be fetch from
> the descriptor. Unfortunately, the PROT bit is not updated with this
> method, we have to do it manually before enabling the channel.
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
> ---
> drivers/dma/at_xdmac.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index cf1213d..52ca1cc 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -359,18 +359,19 @@ static void at_xdmac_start_xfer(struct at_xdmac_chan *atchan,
> * descriptor view 2 since some fields of the configuration register
> * depend on transfer size and src/dest addresses.
> */
> - if (at_xdmac_chan_is_cyclic(atchan)) {
> + if (at_xdmac_chan_is_cyclic(atchan))
> reg = AT_XDMAC_CNDC_NDVIEW_NDV1;
> - at_xdmac_chan_write(atchan, AT_XDMAC_CC, first->lld.mbr_cfg);
> - } else if (first->lld.mbr_ubc & AT_XDMAC_MBR_UBC_NDV3) {
> + else if (first->lld.mbr_ubc & AT_XDMAC_MBR_UBC_NDV3)
> reg = AT_XDMAC_CNDC_NDVIEW_NDV3;
> - } else {
> - /*
> - * No need to write AT_XDMAC_CC reg, it will be done when the
> - * descriptor is fecthed.
> - */
> + else
> reg = AT_XDMAC_CNDC_NDVIEW_NDV2;
> - }
> + /*
> + * Even if the register will be updated from the configuration in the
> + * descriptor when using view 2 or higher, the PROT bit won't be set
> + * properly. This bit can be modified only by using the channel
> + * configuration register.
> + */
> + at_xdmac_chan_write(atchan, AT_XDMAC_CC, first->lld.mbr_cfg);
>
> reg |= AT_XDMAC_CNDC_NDDUP
> | AT_XDMAC_CNDC_NDSUP
> --
> 2.2.0
>


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