Re: [PATCH v3 6/8] dmaengine: rcar-dmac: add iommu support for slave transfers

[Laurent Pinchart]

Hi Niklas,

Thank you for the patch.

On Wednesday 10 February 2016 01:57:56 Niklas Söderlund wrote:
> Enable slave transfers to devices behind IPMMU:s by mapping the slave
> addresses using the dma-mapping API.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
>  drivers/dma/sh/rcar-dmac.c | 57 +++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 52 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index 743873c..268407c 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -1106,21 +1106,68 @@ rcar_dmac_prep_dma_cyclic(struct dma_chan *chan,
> dma_addr_t buf_addr, return desc;
>  }
> 
> +static int rcar_dmac_set_slave_addr(struct dma_chan *chan,
> +				     struct rcar_dmac_chan_slave *slave,
> +				     phys_addr_t addr, size_t size)
> +{
> +	struct dma_attrs attrs;
> +	enum dma_data_direction dir;
> +
> +	init_dma_attrs(&attrs);
> +	dma_set_attr(DMA_ATTR_NO_KERNEL_MAPPING, &attrs);
> +	dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
> +
> +	/*
> +	 * We can't know the direction at this time, see documentation for
> +	 * 'direction' in struct dma_slave_config.
> +	 */
> +	dir = DMA_BIDIRECTIONAL;
> +
> +	if (slave->xfer_size) {
> +		dma_unmap_resource(chan->device->dev, slave->slave_addr,
> +				slave->xfer_size, dir, &attrs);

Nitpicking, you can align slave with chan on the previous line.

> +		slave->slave_addr = 0;
> +		slave->xfer_size = 0;
> +	}
> +
> +	if (size) {
> +		slave->slave_addr = dma_map_resource(chan->device->dev, addr,
> +				size, dir, &attrs);
> +
> +		if (dma_mapping_error(chan->device->dev, slave->slave_addr)) {
> +			struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
> +
> +			dev_err(chan->device->dev,
> +					"chan%u: failed to map %zx@%pap",
> +					rchan->index, size, &addr);

Indentation looks weird to me.

> +			return -EIO;
> +		}
> +
> +		slave->xfer_size = size;
> +	}
> +
> +	return 0;
> +}
> +
>  static int rcar_dmac_device_config(struct dma_chan *chan,
>  				   struct dma_slave_config *cfg)
>  {
>  	struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
> +	int ret;
> 
>  	/*
>  	 * We could lock this, but you shouldn't be configuring the
>  	 * channel, while using it...
>  	 */
> -	rchan->src.slave_addr = cfg->src_addr;
> -	rchan->dst.slave_addr = cfg->dst_addr;
> -	rchan->src.xfer_size = cfg->src_addr_width;
> -	rchan->dst.xfer_size = cfg->dst_addr_width;
> 
> -	return 0;
> +	ret = rcar_dmac_set_slave_addr(chan, &rchan->src, cfg->src_addr,
> +			cfg->src_addr_width);
> +	if (ret)
> +		return ret;
> +
> +	ret = rcar_dmac_set_slave_addr(chan, &rchan->dst, cfg->dst_addr,
> +			cfg->dst_addr_width);

You could align cfg with chan on the previous line (twice).

With this fixed and the attributes removed as explained by Robin,

Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

> +	return ret;
>  }
> 
>  static int rcar_dmac_chan_terminate_all(struct dma_chan *chan)

-- 
Regards,

Laurent Pinchart