Re: [PATCH v5 1/3] dma: imx-sdma: add support for sdma memory copy

[Robin Gong <b38343@freescale.com>]

On Fri, Dec 05, 2014 at 10:09:18PM +0530, Vinod Koul wrote:
> On Thu, Oct 23, 2014 at 10:22:18AM +0800, Robin Gong wrote:
>  
> > -static struct dma_async_tx_descriptor *sdma_prep_slave_sg(
> > -		struct dma_chan *chan, struct scatterlist *sgl,
> > -		unsigned int sg_len, enum dma_transfer_direction direction,
> > -		unsigned long flags, void *context)
> > +static struct dma_async_tx_descriptor *sdma_prep_memcpy(
> > +		struct dma_chan *chan, dma_addr_t dma_dst,
> > +		dma_addr_t dma_src, size_t len, unsigned long flags)
> > +{
> > +	struct sdma_channel *sdmac = to_sdma_chan(chan);
> > +	struct sdma_engine *sdma = sdmac->sdma;
> > +	int channel = sdmac->channel;
> > +	size_t count;
> > +	int i = 0, param, ret;
> > +	struct sdma_buffer_descriptor *bd;
> > +
> > +	if (!chan || !len || sdmac->status == DMA_IN_PROGRESS)
> > +		return NULL;
> why is this dependent on status. You can prepare a descriptor here!
Unfortunately, it is the limitation of imx-sdma driver, the driver can't support
process asynchronously.
> > +
> > +	if (len >= NUM_BD * SDMA_BD_MAX_CNT) {
> > +		dev_err(sdma->dev, "channel%d: maximum bytes exceeded:%d > %d\n",
> > +			channel, len, NUM_BD * SDMA_BD_MAX_CNT);
> > +		goto err_out;
> > +	}
> > +
> > +	sdmac->status = DMA_IN_PROGRESS;
> ??
> 
> > +
> > +	sdmac->buf_tail = 0;
> > +
> > +	dev_dbg(sdma->dev, "memcpy: %x->%x, len=%d, channel=%d.\n",
> > +		dma_src, dma_dst, len, channel);
> > +
> > +	sdmac->direction = DMA_MEM_TO_MEM;
> > +
> > +	ret = sdma_load_context(sdmac);
> > +	if (ret)
> > +		goto err_out;
> > +
> > +	sdmac->chn_count = 0;
> > +
> > +	do {
> > +		count = min_t(size_t, len, SDMA_BD_MAX_CNT);
> > +		bd = &sdmac->bd[i];
> > +		bd->buffer_addr = dma_src;
> > +		bd->ext_buffer_addr = dma_dst;
> > +		bd->mode.count = count;
> > +
> > +		if (sdmac->word_size > DMA_SLAVE_BUSWIDTH_4_BYTES) {
> > +			ret =  -EINVAL;
> > +			goto err_out;
> > +		}
> > +
> > +		switch (sdmac->word_size) {
> > +		case DMA_SLAVE_BUSWIDTH_4_BYTES:
> So are you dependent of dma_slave_config to be set. Then it is wrong. for
> memcpy you shoudn't be!
> 
Yes. Will remove the constrain.
> >  		switch (sdmac->word_size) {
> >  		case DMA_SLAVE_BUSWIDTH_4_BYTES:
> >  			bd->mode.command = 0;
> > -			if (count & 3 || sg->dma_address & 3)
> > +			if ((count | sg_src->dma_address | (sg_dst &&
> > +				(sg_dst->dma_address))) & 3)
> >  				return NULL;
> >  			break;
> >  		case DMA_SLAVE_BUSWIDTH_2_BYTES:
> >  			bd->mode.command = 2;
> > -			if (count & 1 || sg->dma_address & 1)
> > +			if ((count | sg_src->dma_address |
> > +				(sg_dst && (sg_dst->dma_address))) & 1)
> >  				return NULL;
> this doesn't seem to have anything to do with memcpy, shouldn't this be
> independent change here?
> 
Yes, will split the re-org patch clearly.
> >  			break;
> >  		case DMA_SLAVE_BUSWIDTH_1_BYTE:
> > @@ -1099,21 +1214,23 @@ static struct dma_async_tx_descriptor *sdma_prep_slave_sg(
> >  
> >  		param = BD_DONE | BD_EXTD | BD_CONT;
> >  
> > -		if (i + 1 == sg_len) {
> > +		if (i + 1 == src_nents) {
> >  			param |= BD_INTR;
> >  			param |= BD_LAST;
> >  			param &= ~BD_CONT;
> >  		}
> >  
> > -		dev_dbg(sdma->dev, "entry %d: count: %d dma: %#llx %s%s\n",
> > -				i, count, (u64)sg->dma_address,
> > +		dev_dbg(sdma->dev, "entry %d: count: %d dma: 0x%08x %s%s\n",
> > +				i, count, sg_src->dma_address,
> >  				param & BD_WRAP ? "wrap" : "",
> >  				param & BD_INTR ? " intr" : "");
> ditto
> 
> >  
> >  		bd->mode.status = param;
> > +		if (direction == DMA_MEM_TO_MEM)
> > +			sg_dst = sg_next(sg_dst);
> >  	}
> >  
> > -	sdmac->num_bd = sg_len;
> > +	sdmac->num_bd = src_nents;
> >  	sdma->channel_control[channel].current_bd_ptr = sdmac->bd_phys;
> >  
> >  	return &sdmac->desc;
> > @@ -1122,6 +1239,24 @@ err_out:
> >  	return NULL;
> >  }
> >  
> > +static struct dma_async_tx_descriptor *sdma_prep_memcpy_sg(
> > +		struct dma_chan *chan,
> > +		struct scatterlist *dst_sg, unsigned int dst_nents,
> > +		struct scatterlist *src_sg, unsigned int src_nents,
> > +		unsigned long flags)
> > +{
> > +	return sdma_prep_sg(chan, dst_sg, dst_nents, src_sg, src_nents,
> > +			   DMA_MEM_TO_MEM);
> > +}
> > +
> > +static struct dma_async_tx_descriptor *sdma_prep_slave_sg(
> > +		struct dma_chan *chan, struct scatterlist *sgl,
> > +		unsigned int sg_len, enum dma_transfer_direction direction,
> > +		unsigned long flags, void *context)
> > +{
> > +	return sdma_prep_sg(chan, NULL, 0, sgl, sg_len, direction);
> > +}
> you should have done this first and then added memcpy
> 
> -- 
> ~Vinod 
Ok, do the re-org patch firstly, and then add new feature.