[PATCH] dmaengine: at_xdmac: fix bug about channel configuration

[PATCH] dmaengine: at_xdmac: fix bug about channel configuration

[Ludovic Desroches]

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

Re: [PATCH] dmaengine: at_xdmac: fix bug about channel configuration

[Ludovic Desroches]

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
> 

Re: [PATCH] dmaengine: at_xdmac: fix bug about channel configuration

[Vinod Koul]

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.
> 
Applied, thanks

-- 
~Vinod