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authorLudovic Desroches <ludovic.desroches@atmel.com>2015-01-27 16:30:32 +0100
committerVinod Koul <vinod.koul@intel.com>2015-02-05 08:12:29 +0100
commit6d3a7d9e3ada345948f72564ce638c412ccd8c4a (patch)
treed76e829bc3b094b12676cf6ff7220615412da764 /drivers
parentdmaengine: at_xdmac: simplify channel configuration stuff (diff)
downloadlinux-6d3a7d9e3ada345948f72564ce638c412ccd8c4a.tar.xz
linux-6d3a7d9e3ada345948f72564ce638c412ccd8c4a.zip
dmaengine: at_xdmac: allow muliple dwidths when doing slave transfers
When using FIFO, we need to support differents data width in a single transfer. For example, serial device which usually uses 1-byte data width will use 4-bytes data width when using the FIFO. If the transfer size is not aligned on 4-bytes then the end of the transfer will be performed with 1-byte data-width. For that reason, at_xdmac_prep_slave_sg() now builds linked list descriptors using view 2 instead of view 1 so each of them can update the DWIDTH field into the Channel Configuration Register. Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com> Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/dma/at_xdmac.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index eba66a22a265..09e2825a547a 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -25,6 +25,7 @@
#include <linux/dmapool.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
+#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of_dma.h>
@@ -351,11 +352,11 @@ static void at_xdmac_start_xfer(struct at_xdmac_chan *atchan,
at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, reg);
/*
- * When doing memory to memory transfer we need to use the next
+ * When doing non cyclic transfer we need to use the next
* descriptor view 2 since some fields of the configuration register
* depend on transfer size and src/dest addresses.
*/
- if (is_slave_direction(first->direction)) {
+ if (at_xdmac_chan_is_cyclic(atchan)) {
reg = AT_XDMAC_CNDC_NDVIEW_NDV1;
at_xdmac_chan_write(atchan, AT_XDMAC_CC, first->lld.mbr_cfg);
} else {
@@ -582,7 +583,7 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
/* Prepare descriptors. */
for_each_sg(sgl, sg, sg_len, i) {
struct at_xdmac_desc *desc = NULL;
- u32 len, mem;
+ u32 len, mem, dwidth, fixed_dwidth;
len = sg_dma_len(sg);
mem = sg_dma_address(sg);
@@ -613,11 +614,15 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
desc->lld.mbr_da = atchan->per_dst_addr;
desc->lld.mbr_cfg = atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG];
}
- desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV1 /* next descriptor view */
+ dwidth = at_xdmac_get_dwidth(desc->lld.mbr_cfg);
+ fixed_dwidth = IS_ALIGNED(len, 1 << dwidth)
+ ? at_xdmac_get_dwidth(desc->lld.mbr_cfg)
+ : AT_XDMAC_CC_DWIDTH_BYTE;
+ desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV2 /* next descriptor view */
| AT_XDMAC_MBR_UBC_NDEN /* next descriptor dst parameter update */
| AT_XDMAC_MBR_UBC_NSEN /* next descriptor src parameter update */
| (i == sg_len - 1 ? 0 : AT_XDMAC_MBR_UBC_NDE) /* descriptor fetch */
- | len / (1 << at_xdmac_get_dwidth(desc->lld.mbr_cfg)); /* microblock length */
+ | (len >> fixed_dwidth); /* microblock length */
dev_dbg(chan2dev(chan),
"%s: lld: mbr_sa=%pad, mbr_da=%pad, mbr_ubc=0x%08x\n",
__func__, &desc->lld.mbr_sa, &desc->lld.mbr_da, desc->lld.mbr_ubc);