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SubjectRe: [PATCH 4/7] dmaengine: at_xdmac: adapt perid for mem2mem operations
Date
On 9/14/20 5:09 PM, Eugen Hristev wrote:
> The PERID in the CC register for mem2mem operations must match an unused
> PERID.
> The PERID field is 7 bits, but the selected value is 0x3f.
> On later products we can have more reserved PERIDs for actual peripherals,
> thus this needs to be increased to maximum size.
> Changing the value to 0x7f, which is the maximum for 7 bits field.
>

Maybe it is worth to explain that for memory-to-memory transfers, PERID
should be set to an unused peripheral ID, and the maximum value seems the
safest. Anyway with or without this addressed, one can add:

Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>

> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
> drivers/dma/at_xdmac.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index fab19e00a7be..81bb90206092 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -726,7 +726,7 @@ at_xdmac_interleaved_queue_desc(struct dma_chan *chan,
> * match the one of another channel. If not, it could lead to spurious
> * flag status.
> */
> - u32 chan_cc = AT_XDMAC_CC_PERID(0x3f)
> + u32 chan_cc = AT_XDMAC_CC_PERID(0x7f)
> | AT_XDMAC_CC_DIF(0)
> | AT_XDMAC_CC_SIF(0)
> | AT_XDMAC_CC_MBSIZE_SIXTEEN
> @@ -908,7 +908,7 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> * match the one of another channel. If not, it could lead to spurious
> * flag status.
> */
> - u32 chan_cc = AT_XDMAC_CC_PERID(0x3f)
> + u32 chan_cc = AT_XDMAC_CC_PERID(0x7f)
> | AT_XDMAC_CC_DAM_INCREMENTED_AM
> | AT_XDMAC_CC_SAM_INCREMENTED_AM
> | AT_XDMAC_CC_DIF(0)
> @@ -1014,7 +1014,7 @@ static struct at_xdmac_desc *at_xdmac_memset_create_desc(struct dma_chan *chan,
> * match the one of another channel. If not, it could lead to spurious
> * flag status.
> */
> - u32 chan_cc = AT_XDMAC_CC_PERID(0x3f)
> + u32 chan_cc = AT_XDMAC_CC_PERID(0x7f)
> | AT_XDMAC_CC_DAM_UBS_AM
> | AT_XDMAC_CC_SAM_INCREMENTED_AM
> | AT_XDMAC_CC_DIF(0)
>

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