[PATCH v6 1/3] dma: at_xdmac: creation of the atmel eXtended DMA Controller driver

[Ludovic Desroches]

Hi Vinod,

On Wed, Oct 15, 2014 at 07:00:04PM +0530, Vinod Koul wrote:
> On Wed, Oct 01, 2014 at 04:59:23PM +0200, Ludovic Desroches wrote:
> > New atmel DMA controller known as XDMAC, introduced with SAMA5D4
> > devices.
> > 
> > +static int at_xdmac_set_slave_config(struct dma_chan *chan,
> > +				      struct dma_slave_config *sconfig)
> > +{
> > +	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
> > +
> > +	atchan->cfg = AT91_XDMAC_DT_PERID(atchan->perid)
> > +		      |	AT_XDMAC_CC_SWREQ_HWR_CONNECTED
> > +		      | AT_XDMAC_CC_MBSIZE_SIXTEEN
> > +		      | AT_XDMAC_CC_TYPE_PER_TRAN;
> > +
> > +	if (sconfig->direction == DMA_DEV_TO_MEM) {
> > +		atchan->cfg |= AT_XDMAC_CC_DAM_INCREMENTED_AM
> > +			       | AT_XDMAC_CC_SAM_FIXED_AM
> > +			       | AT_XDMAC_CC_DIF(atchan->memif)
> > +			       | AT_XDMAC_CC_SIF(atchan->perif)
> > +			       | AT_XDMAC_CC_DSYNC_PER2MEM;
> > +		atchan->dwidth = ffs(sconfig->src_addr_width) - 1;
> > +		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
> > +		atchan->cfg |= at_xdmac_csize(sconfig->src_maxburst);
> > +	} else if (sconfig->direction == DMA_MEM_TO_DEV) {
> > +		atchan->cfg |= AT_XDMAC_CC_DAM_FIXED_AM
> > +			       | AT_XDMAC_CC_SAM_INCREMENTED_AM
> > +			       | AT_XDMAC_CC_DIF(atchan->perif)
> > +			       | AT_XDMAC_CC_SIF(atchan->memif)
> > +			       | AT_XDMAC_CC_DSYNC_MEM2PER;
> > +		atchan->dwidth = ffs(sconfig->dst_addr_width) - 1;
> > +		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
> > +		atchan->cfg |= at_xdmac_csize(sconfig->dst_maxburst);
> please store both direction configs and use them based on direction in
> prep_xxx calls. We will remove the direction here.
> 

Ok so direction will disappear the dma_slave_config structure I assume
but what is planned for src/dst_addr_width and src/dst_maxburst. If
slave config looses the direction, there is no sense to have some src
and dst fields. So where should I get them?

> > +	} else {
> > +		return -EINVAL;
> > +	}
> > +
> > +	/*
> > +	 * Src address and dest addr are needed to configure the link list
> > +	 * descriptor so keep the slave configuration.
> > +	 */
> > +	memcpy(&atchan->dma_sconfig, sconfig, sizeof(struct dma_slave_config));
> > +
> > +	dev_dbg(chan2dev(chan), "%s: atchan->cfg=0x%08x\n", __func__, atchan->cfg);
> > +
> > +	return 0;
> > +}

Ludovic