The dw_dmac driver was earlier adapted to do 64-bit transfers on the memory side (https://lkml.org/lkml/2012/1/18/52) This works on ARM platforms but for AVR32 (AP700x) the maximum allowed transfer size is 32-bits. This patch allows the arch to set a new slave property max_mem_width to limit the size. Allowable values for dw_dma_slave::max_mem_width are:
0 : leave it up to dw_dmac (64 bits) 1 : 16-bits 2 : 32-bits Signed-off-by: Hein Tibosch <hein_tibo...@yahoo.es> --- drivers/dma/dw_dmac.c | 8 ++++++++ include/linux/dw_dmac.h | 3 +++ 2 files changed, 11 insertions(+), 0 deletions(-) diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c index 7212961..a4bdf1d 100644 --- a/drivers/dma/dw_dmac.c +++ b/drivers/dma/dw_dmac.c @@ -754,6 +754,10 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, mem_width = 1; else mem_width = 0; + /* Some controllers don't support 64-bits mem access */ + if (dws->max_mem_width && + mem_width > dws->max_mem_width) + mem_width = dws->max_mem_width; slave_sg_todev_fill_desc: desc = dwc_desc_get(dwc); @@ -821,6 +825,10 @@ slave_sg_todev_fill_desc: mem_width = 1; else mem_width = 0; + /* Some controllers don't support 64-bits mem access */ + if (dws->max_mem_width && + mem_width > dws->max_mem_width) + mem_width = dws->max_mem_width; slave_sg_fromdev_fill_desc: desc = dwc_desc_get(dwc); diff --git a/include/linux/dw_dmac.h b/include/linux/dw_dmac.h index 2412e02..60b01c3 100644 --- a/include/linux/dw_dmac.h +++ b/include/linux/dw_dmac.h @@ -51,6 +51,8 @@ enum dw_dma_msize { * @cfg_lo: Platform-specific initializer for the CFG_LO register * @src_master: src master for transfers on allocated channel. * @dst_master: dest master for transfers on allocated channel. + * @max_mem_width: max value for SRC/DST_TR_WIDTH register + * default 0 means: leave it up to driver */ struct dw_dma_slave { struct device *dma_dev; @@ -58,6 +60,7 @@ struct dw_dma_slave { u32 cfg_lo; u8 src_master; u8 dst_master; + u8 max_mem_width; }; /* Platform-configurable bits in CFG_HI */ -- 1.7.8.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/