Re: [PATCH v5 2/3] dmaengine: ti: edma: Correct the residue calculation (fix for memcpy)

[Vinod Koul <vkoul@kernel.org>]

On 16-07-19, 11:26, Peter Ujfalusi wrote:
> For memcpy we never stored the start address of the transfer for the pset
> which rendered the memcpy residue calculation completely broken.
> 
> In the edma_residue() function we also need to to some correction for the
> calculations:
> Instead waiting for all EDMA channels to be idle (in a busy system it can
> take few iteration to hit a point when all queues are idle) wait for the
> event pending on the given channel (SH_ER for hw synchronized channels,
> SH_ESR for manually triggered channels).
> 
> If the position returned by EMDA is 0 it imiplies that the last paRAM set

s/imiplies/implies

> has been consumed and we are at the closing dummy set, thus we can conclude
> that the transfer is completed and we can return 0 as residue.
> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> ---
>  drivers/dma/ti/edma.c | 31 +++++++++++++++++++++++--------
>  1 file changed, 23 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/dma/ti/edma.c b/drivers/dma/ti/edma.c
> index a39f817b3888..5b8cbd6d7610 100644
> --- a/drivers/dma/ti/edma.c
> +++ b/drivers/dma/ti/edma.c
> @@ -1026,6 +1026,7 @@ static int edma_config_pset(struct dma_chan *chan, struct edma_pset *epset,
>  		src_cidx = cidx;
>  		dst_bidx = acnt;
>  		dst_cidx = cidx;
> +		epset->addr = src_addr;
>  	} else {
>  		dev_err(dev, "%s: direction not implemented yet\n", __func__);
>  		return -EINVAL;
> @@ -1736,7 +1737,11 @@ static u32 edma_residue(struct edma_desc *edesc)
>  	int loop_count = EDMA_MAX_TR_WAIT_LOOPS;
>  	struct edma_chan *echan = edesc->echan;
>  	struct edma_pset *pset = edesc->pset;
> -	dma_addr_t done, pos;
> +	dma_addr_t done, pos, pos_old;
> +	int channel = EDMA_CHAN_SLOT(echan->ch_num);
> +	int idx = EDMA_REG_ARRAY_INDEX(channel);
> +	int ch_bit = EDMA_CHANNEL_BIT(channel);
> +	int event_reg;
>  	int i;
>  
>  	/*
> @@ -1749,16 +1754,20 @@ static u32 edma_residue(struct edma_desc *edesc)
>  	 * "pos" may represent a transfer request that is still being
>  	 * processed by the EDMACC or EDMATC. We will busy wait until
>  	 * any one of the situations occurs:
> -	 *   1. the DMA hardware is idle
> -	 *   2. a new transfer request is setup
> +	 *   1. while and event is pending for the channel
> +	 *   2. a position updated
>  	 *   3. we hit the loop limit
>  	 */
> -	while (edma_read(echan->ecc, EDMA_CCSTAT) & EDMA_CCSTAT_ACTV) {
> -		/* check if a new transfer request is setup */
> -		if (edma_get_position(echan->ecc,
> -				      echan->slot[0], dst) != pos) {
> +	if (is_slave_direction(edesc->direction))
> +		event_reg = SH_ER;
> +	else
> +		event_reg = SH_ESR;
> +
> +	pos_old = pos;
> +	while (edma_shadow0_read_array(echan->ecc, event_reg, idx) & ch_bit) {
> +		pos = edma_get_position(echan->ecc, echan->slot[0], dst);
> +		if (pos != pos_old)
>  			break;
> -		}
>  
>  		if (!--loop_count) {
>  			dev_dbg_ratelimited(echan->vchan.chan.device->dev,
> @@ -1783,6 +1792,12 @@ static u32 edma_residue(struct edma_desc *edesc)
>  		return edesc->residue_stat;
>  	}
>  
> +	/*
> +	 * If the position is 0, then EDMA loaded the closing dummy slot, the
> +	 * transfer is completed
> +	 */
> +	if (!pos)
> +		return 0;
>  	/*
>  	 * For SG operation we catch up with the last processed
>  	 * status.
> -- 
> Peter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

-- 
~Vinod